88 Answered Test Questions:
1. Which of the following is true about setTimeOut()?
Answers:
• The statement(s) it executes run(s) only once.
• It pauses the script in which it is called.
• clearTimeOut() won't stop its execution.
• The delay is measured in hundredths of a second.
• It is required in every JavaScript function.
2. How can the operating system of the client machine be detected?
Answers:
• It is not possible using JavaScript.
• Using the navigator object
• Using the window object
• Using the document object
• None of these.
3. Which of the following prints "AbBc"?
Answers:
• var b = 'a'; var result = b.toUpperCase() + 'b' + 'b'.toUpperCase() +'C'['toLowerCase'](); alert(result);
• var b = 'a'; var result = b.toUpperCase() + 'b' + 'b'.toUpperCase() +'c'['toUpperCase'](); alert(result);
• var b = 'a'; var result = b.toUpperCase() + b + 'b'.toUpperCase() +'C'['toLowerCase'](); alert(result);
• var b = 'a'; var result = b.toUpperCase() + 'b' + 'b'.toUpperCase() +C; alert(result);
4. Which of the following descriptions is true for the code below?
var object0 = {};
Object.defineProperty(object0, "prop0", { value : 1, enumerable:false, configurable : true });
Object.defineProperty(object0, "prop1", { value : 2, enumerable:true, configurable : false });
Object.defineProperty(object0, "prop2", { value : 3 });
object0.prop3 = 4;
Answers:
• Object 'object0' contains 4 properties. Property 'prop2' and property 'prop3' are available in the for...in loop. Property 'prop0' and property 'prop1' are available to delete.
• Object 'object0' contains 4 properties. Property 'prop1' and property 'prop2' are available in the for...in loop. Property 'prop2' and property 'prop3' are available to delete.
• Object 'object0' contains 4 properties. Property 'prop0' and property 'prop2' are available in the for...in loop. Property 'prop0' and property 'prop2' are available to delete.
• Object 'object0' contains 4 properties. Property 'prop1' and property 'prop3' are available in the for...in loop. Property 'prop0' and property 'prop3' are available to delete.
5. Performance-wise, which is the fastest way of repeating a string in JavaScript?
Answers:
• String.prototype.repeat = function( num ) { return new Array( num + 1 ).join( this ); }
• function repeat(pattern, count) { if (count < 1) return ''; var result = ''; while (count > 0) { if (count & 1) result += pattern; count >>= 1, pattern += pattern; } return result; }
• String.prototype.repeat = function(count) { if (count < 1) return ''; var result = '', pattern = this.valueOf(); while (count > 0) { if (count & 1) result += pattern; count >>= 1, pattern += pattern; } return result; };
• String.prototype.repeat = function (n, d) { return --n ? this + (d || '') + this.repeat(n, d) : '' + this };
6. Consider the following variable declarations:
var a="adam"
var b="eve"
Which of the following would return the sentence "adam and eve"?
Answers:
• a.concatinate("and", b)
• a.concat("and", b)
• a.concatinate(" and ", b)
• a.concat(" and ", b)
7. Which of the following code snippets will correctly split "str"?
Answers:
• <script> var str = 'something -- something_else'; var substrn = str.split(' -- '); </script>
• <script> var str = 'something -- something_else'; var substrn = split.str(' --- '); </script>
• <script> var str = 'something -- something_else'; var substrn = str.split(' - ',' - '); </script>
• <script> var str = 'something -- something_else'; var substrn = split.str(' - ',' - '); </script>
8. Which object can be used to ascertain the protocol of the current URL?
Answers:
• document
• window
• history
• browser
• form
• location
9. Which of the following best describes a "for" loop?
Answers:
• "for" loop consists of six optional expressions, enclosed in parentheses and separated by semicolons, followed by a statement executed in the loop.
• "for" loop consists of five optional expressions, enclosed in parentheses and separated by semicolons, followed by a statement executed in the loop.
• "for" loop consists of four optional expressions, enclosed in parentheses and separated by semicolons, followed by a statement executed in the loop.
• "for" loop consists of three optional expressions, enclosed in parentheses and separated by semicolons, followed by a statement executed in the loop.
10. Which of the following descriptions best describes the code below?
<script>
var variable1 = { fastFood: "spaghetti", length: 10 };
Object.freeze(variable1);
variable1.price = 50;
delete variable1.length;
</script>
Answers:
• Object is frozen, a property named "price" is added in the variable1 object, a property named "length" is deleted from this object. At the end of the code, the object "variable1" contains 2 properties.
• Object is frozen, a property named "price" is not added in the variable1 object, a property named "length" is deleted from this object. At the end of the code, object "variable1" contains 1 properties.
• Object is frozen, a property named "price" is added in the variable1 object, a property named "length" is not deleted from this object. At the end of the code, object "variable1" contains 1 properties.
• Object is frozen, a property named "price" is not added in the variable1 object, a property named "length" is not deleted from this object. At the end of the code, object "variable1" contains 2 properties.
11. Which of the following is not a valid HTML event?
Answers:
• ondblclick
• onmousemove
• onclick
• onblink
12. Analyze the following code snippet which uses a Javascript Regular Expression character set. What will be the output of this code?
<html>
<body>
<script type="text/javascript">
var str = "Is this enough?";
var patt1 = new RegExp("[^A-J]");
var result = str.match(patt1);
document.write(result);
</script>
</body>
</html
Answers:
• I
• Is
• s
• I,s,
13. Consider the following image definition:
<img id="logo" src="companylogo1.gif" height="12" width="12" >
Which of the following will change the image to companylogo2.gif when the page loads?
Answers:
• logo.source="companylogo2.gif"
• logo.source="companylogo1.gif"
• document.getElementById('logo').src="companylogo1.gif"
• document.getElementById('logo').src="companylogo2.gif"
14. What is the final value of the variable bar in the following code?
var foo = 9;
bar = 5;
(function() {
var foo = 2;
bar= 1;
}())
bar = bar + foo;
Answers:
• 10
• 14
• 3
• 7
15. Which of the following are JavaScript unit testing tools?
Answers:
• Buster.js, jQuery, YUI Yeti
• QUnit, Modernizr, JsTestDriver
• Node.js, Modernizr, Jasmine
• Buster.js, YUI Yeti, Jasmine
16. Which of the following can be used for disabling the right click event in Internet Explorer?
Answers:
• event.button == 2
• event.button == 4
• event.click == 2
• event.click == 4
17. An image tag is defined as follows:
<img id="ERImage" width="100" height="100" onmouseover="ImageChange()" src="Image1.jpg">
The purpose of the ImageChange() function is to change the image source to Image2.jpg. Which of the following should the ImageChange() function look like?
Answers:
• document.getElementById('ERImage').src="Image1.jpg"
• document.getElementById('ERImage').src="Image2.jpg"
• document.getElementById('ERImage').style.src="Image1.jpg"
• document.getElementById('ERImage').style.src="Image2.jpg"
18. Consider the following JavaScript alert:
<script type="text/JavaScript">
function message() {
alert("Welcome to ExpertRating!!!")
}
</script>
Which of the following will run the function when a user opens the page?
Answers:
• body onload="message()"
• body onunload="message()"
• body onsubmit="message()"
• body onreset="message()"
19. Which of the following code snippets will correctly get the length of an object?
Answers:
• <script> var newObj = new Object(); newObj["firstname"] = "FirstName"; newObj["lastname"] = "LastName"; newObj["age"] = 21; Object.size = function(obj) { var size = 0, key; for (key in obj) { if (obj.hasOwnProperty(index)) size++; } return size; }; var size = Object.size(newObj); </script>
• <script> var newObj = new Object(); newObj["firstname"] = "FirstName"; newObj["lastname"] = "LastName"; newObj["age"] = 21; Object.size = function(obj) { var size = 0, key; for (key in obj) { if (obj.hasOwnProperty(value)) size++; } return size; }; var size = Object.size(newObj); </script>
• <script> var newObj = new Object(); newObj["firstname"] = "FirstName"; newObj["lastname"] = "LastName"; newObj["age"] = 21; Object.size = function(obj) { var size = 0, key; for (key in obj) { if (obj.hasOwnProperty(length)) size++; } return size; }; var size = Object.size(newObj); </script>
• <script> var newObj = new Object(); newObj["firstname"] = "FirstName"; newObj["lastname"] = "LastName"; newObj["age"] = 21; Object.size = function(obj) { var size = 0, key; for (key in obj) { if (obj.hasOwnProperty(key)) size++; } return size; }; var size = Object.size(newObj); </script>
20. Which of the following Array methods in JavaScript runs a function on every item in the Array and collects the result from previous calls, but in reverse?
Answers:
• reduce()
• reduceRight()
• reverse()
• pop()
21. In an HTML page, the form tag is defined as follows:
<form onsubmit="return Validate()" action="http://www.mysite.com/">
The validate() function is intended to prevent the form from being submitted if the name field in the form is empty. What should the validate() function look like?
Answers:
• <script type="text/javascript"> function Validate() { if(document.forms[0].name.value == "") return true; else return false; } </script>
• <script type="text/javascript"> function Validate() { if(document.forms[0].name.value == "") return false; else return true; } </script>
• script type="text/javascript"> function Validate() { if(document.forms[0].name== "") return false; else return true; } </script>
• <script type="text/javascript"> function Validate() { if(document.forms[0].name == "") return true; else return false; } </script>
22. Which of the following code snippets changes an image on the page?
Answers:
• var img = document.getElementById("imageId"); img.src = "newImage.gif";
• var img = document.getElementById("imageId"); img.style.src = "newImage.gif";
• var img = document.getElementById("imageId"); img.src.value = "newImage.gif";
• var img = document.getElementById("imageId"); img = "newImage.gif";
23. Which of the following results is returned by the JavaScript operator "typeof" for the keyword "null"?
Answers:
• function
• object
• string
• number
24. What will be the final value of the variable "apt"?
var apt=2;
apt=apt<<2;
Answers:
• 2
• 4
• 6
• 8
• 16
25. How can a JavaScript object be printed?
Answers:
• console.log(obj)
• console.print(obj)
• console.echo(obj);
• None of these
26. Which of the following is the correct syntax for using the JavaScript exec() object method?
Answers:
• RegExpObject.exec()
• RegExpObject.exec(string)
• RegExpObject.exec(parameter1,parameter2)
• None of these
27. Having an array object var arr = new Array(), what is the best way to add a new item to the end of an array?
Answers:
• arr.push("New Item")
• arr[arr.length] = "New Item"
• arr.unshift("New Item")
• arr.append("New Item")
28. Consider the following JavaScript validation function:
function ValidateField()
{
if(document.forms[0].txtId.value =="")
{return false;}
return true;
}
Which of the following options will call the function as soon as the user leaves the field?
Answers:
• input name=txtId type="text" onreset="return ValidateField()"
• input name=txtId type="text" onfocus="return ValidateField()"
• input name=txtId type="text" onsubmit="return ValidateField()"
• input name=txtId type="text" onblur="return ValidateField()"
29. Which of following uses the "with" statement in JavaScript correctly?
Answers:
• with (document.getElementById("blah").style) { background = "black"; color = "blue"; border = "1px solid green"; }
• with document.getElementById("blah").style background = "black"; color = "blue"; border = "1px solid green"; End With
• With document.getElementByName("blah").style background = "black"; color = "blue"; border = "1px solid green"; End With
• with (document.getElementById("blah").style) { .background = "black"; .color = "blue"; .border = "1px solid green"; }
30. Consider the following JavaScript validation function:
<script type="text/JavaScript">
function ValidateField()
{
if(document.forms[0].txtId.value =="")
{return false;}
return true;
}
</script>
Which of the following options will call the function as soon as the user leaves the field?
Answers:
• input name=txtId type="text" onreset="return ValidateField()"
• input name=txtId type="text" onfocus="return ValidateField()"
• input name=txtId type="text" onsubmit="return ValidateField()"
• input name=txtId type="text" onblur="return ValidateField()"
31. Which of the following modifiers must be set if the JavaScript lastIndex object property was used during pattern matching?
Answers:
• i
• m
• g
• s
32. Consider the following image definition:
<img id="logo" src="companylogo1.gif" height="12" width="12" >
Which of the following will change the image to "companylogo2.gif" when the page loads?
Answers:
• logo.source="companylogo2.gif"
• logo.source="companylogo1.gif"
• document.getElementById('logo').src="companylogo1.gif"
• document.getElementById('logo').src="companylogo2.gif"
33. Which of the following will check whether the variable vRast exists or not?
Answers:
• if (typeof vRast="undefined") {}
• if (typeof vRast =="undefined") {}
• if (vRast.defined =true) {}
• if (vRast.defined ==true) {}
34. What would be the use of the following code?
function validate(field) {
var valid=''ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz'';
var ok=''yes'';
var temp;
for(var i=0;i<field.value.length;i++) {
temp='''' + field.value.substring(i,i+1)
if(valid.indexOf(temp)==''-1'') {
ok=''no'';
}
}
if(ok==''no'') {
alert(''error'');
field.focus();
}
}
Answers:
• It will force a user to enter only numeric values.
• It will force a user to enter only alphanumeric values.
• It will force a user to enter only English alphabet character values.
• None of these.
35. An image tag is defined as follows:
<img id="ERImage" width="100" height="100" onmouseover="ImageChange()" src="Image1.jpg">
The purpose of the ImageChange() function is to change the image source to "Image2.jpg". Which of the following should the ImageChange() function look like?
Answers:
• document.getElementById('ERImage').src="Image1.jpg"
• document.getElementById('ERImage').src="Image2.jpg"
• document.getElementById('ERImage').style.src="Image1.jpg"
• document.getElementById('ERImage').style.src="Image2.jpg"
36. Which of the following choices will detect if "variableName" declares a function?
<script>
var variableName= function(){};
</script>
Answers:
• return variableName;
• nameof variableName;
• isFunction variableName;
• typeof variableName;
37. Which of the following choices will change the source of the image to "image2.gif" when a user clicks on the image?
Answers:
• img id="imageID" src="image1.gif" width="50" height="60" onmousedown="changeimg(image1.gif)" onmouseup="changeimg(image2.gif)"
• img id="imageID" src="image1.gif" width="50" height="60" onmouseclick="changeimg(image2.gif)" onmouseup="changeimg(image1.gif)"
• img id="imageID" src="image2.gif" width="50" height="60" onmousedown="changeimg(image1.gif)" onmouseup="changeimg(image2.gif)"
• img id="imageID" src="image2.gif" width="50" height="60" onmousedown="changeimg(image2.gif)" onmouseup="changeimg(image1.gif)"
• img id="imageID" src="image1.gif" width="50" height="60" onmousedown="changeimg('image2.gif')" onmouseup="changeimg('image1.gif')"
38. How can created cookies be deleted using JavaScript?
Answers:
• They can't be deleted. They are valid until they expire.
• Overwrite with an expiry date in the past
• Use escape() on the value of the path attribute
• Use unescape() on the value of the path attribute
• The cookie file will have to be removed from the client machine.
• Wait till the expiry date is reached
39. What would be the value of 'ind' after execution of the following code?
var msg="Welcome to ExpertRating"
var ind= msg.substr(3, 3)
Answers:
• lco
• com
• ome
• Welcome
40. Are the two statements below interchangeable?
object.property
object[''property'']
Answers:
• Yes
• No
41. Which of the following is not a valid method in generator-iterator objects in JavaScript?
Answers:
• send()
• throw()
• next()
• stop()
42. Which of the following code snippets will return all HTTP headers?
Answers:
• var req = new XMLHttpRequest(); req.open('GET', document.location, false); req.send(null); var headers = req.getAllResponseHeaders().toLowerCase(); alert(headers);
• var req = new XMLHttpAccess(); req.open('GET', document.location, false); req.send(null); var headers = req.getAllResponseHeaders().toLowerCase(); alert(headers);
• var req = new XMLHttpRequest(); req.open('GET', document.location, false); req.send(null); var headers = req.getResponseHeader().toLowerCase(); alert(headers);
• var req = new XMLHttpRequestHeader(); req.open('GET', document.location, false); req.send(null); var headers = req.retrieveAllResponseHeaders().toLowerCase(); alert(headers);
43. Consider the following JavaScript alert:
<script type="text/JavaScript">
function message() {
alert("Welcome to ExpertRating!!!")
}
</script>
Which of the following will run the function when a user opens the page?
Answers:
• body onload="message()"
• body onunload="message()"
• body onsubmit="message()"
• body onreset="message()"
44. Which of the following is the most secure and efficient way of declaring an array?
Answers:
• var a = []
• var a = new Array()
• var a = new Array(n)
• var a
45. Which of the following Regular Expression pattern flags is not valid?
Answers:
• gi
• p
• i
• g
46. Which of the following built-in functions is used to access form elements using their IDs?
Answers:
• getItem(id)
• getFormElement(id)
• getElementById(id)
• All of these
47. Which of the following statements is correct?
Answers:
• There is no undefined property in JavaScript.
• Undefined object properties can be checked using the following code: if (typeof something == null) alert("something is undefined");
• It is not possible to check for undefined object properties in JavaScript.
• Undefined object properties can be checked using the following code: if (typeof something === "undefined") alert("something is undefined");
48. Which of the following correctly uses a timer with a function named rearrange()?
Answers:
• tmr=setTimeout("rearrange ()",1)
• tmr=Timer(1,"rearrange ()")
• tmr=Timer("rearrange ()",1)
• tmr=setTimeout(1,"rearrange ()")
49. Which of the following can be used to escape the ' character?
Answers:
• *
• \
• -
• @
• #
• %
• |
• ~
50. Which event can be used to validate the value in a field as soon as the user moves out of the field by pressing the tab key?
Answers:
• onblur
• onfocus
• lostfocus
• gotfocus
• None of these
51. When setting cookies with JavaScript, what will happen to the cookies.txt data if the file exceeds the maximum size?
Answers:
• The script automatically generates a run-time error.
• The script automatically generates a load-time error.
• All processes using document.cookie are ignored.
• The file is truncated to the maximum length.
52. Which of the following are not global methods and properties in E4X?
Answers:
• ignoreComments
• ignoreWhiteSpace
• setName()
• setNamespace()
• ignoreComments and ignoreWhiteSpace
• setName() and setNamespace()
53. Which of the following will change the color of a paragraph's text to blue when a user hovers over it, and reset it back to black when the user hovers out?
Answers:
• <p onmouseover="style.color='black'" onmouseout="style.color='blue'"> The text of the paragraph..</p>
• <p onmouseover="style.color='blue'" onmouseout="style.color='black'"> The text of the paragraph..</p>
• <p onmouseout="style.color='blue'"> The text of the paragraph..</p>
• <p onmouseover="style.color='blue'"> The text of the paragraph..</p>
• <p onmousein="style.color='blue'" onmouseout="style.color='black'"> The text of the paragraph..</p>
54. What is the purpose of while(1) in the following JSON response?
while(1);[['u',[['smsSentFlag','false'],['hideInvitations','false'],['remindOnRespondedEventsOnly','true'],['hideInvitations_remindOnRespondedEventsOnly','false_true'],['Calendar ID stripped for privacy','false'],['smsVerifiedFlag','true']]]]
Answers:
• It's invalid JSON code.
• It makes it difficult for a third-party to insert the JSON response into an HTML document with a <script> tag.
• It iterates the JSON response.
• It prevents the JSON response from getting executed.
55. Consider the three variables:
someText = 'JavaScript1.2';
pattern = /(\w+)(\d)\.(\d)/i;
outCome = pattern.exec(someText);
What does outCome[0] contain?
Answers:
• true
• false
• JavaScript1.2
• null
• 0
56. Which of the following choices will turn a string into a JavaScript function call (case with objects) of the following code snippet?
<script>
window.foo = {
bar: {
baz: function() {
alert('Hello!');
}
}
};
</script>
Answers:
• bar['baz']();
• object['foo']['bar']['baz']();
• document['foo']['bar']['baz']();
• window['foo']['bar']['baz']();
57. Which of the following determines whether cookies are enabled in a browser or not?
Answers:
• (navigator.Cookie)? true : false
• (application.cookieEnabled)? true : false
• (navigator.cookieEnabled)? true : false
• (application.cookie)? true : false
58. Which of the following options can be used for adding direct support for XML to JavaScript?
Answers:
• E4X
• egex
• Generators and Iterators
• let
59. Which of the following will detect which DOM element has the focus?
Answers:
• document.activeElement
• document.ready
• document.referrer
• document.getelementbyid
60. Which of the following will randomly choose an element from an array named myStuff, given that the number of elements changes dynamically?
Answers:
• randomElement = myStuff[Math.floor(Math.random() * myStuff.length)];
• randomElement = myStuff[Math.ceil(Math.random() * myStuff.length)];
• randomElement = myStuff[Math.random(myStuff.length)];
• randomElement = Math.random(myStuff.length);
61. How can global variables be declared in JavaScript?
Answers:
• All variables are local in JavaScript.
• Declare the variable between the 'script' tags, and outside a function to make the variable global
• Precede the variable name with the constant global
• Declare the variable in an external file
62. Which of the following objects in JavaScript contains the collection called "plugins"?
Answers:
• Location
• Window
• Screen
• Navigator
63. What will be output of the following code?
function testGenerator() {
yield "first";
document.write("step1");
yield "second";
document.write("step2");
yield "third";
document.write("step3");
}
var g = testGenerator();
document.write(g.next());
document.write(g.next());
Answers:
• firststep1second
• step1step2
• step1
• step1step2step3
64. Which of the following methods will copy data to the Clipboard?
Answers:
• execClipboard('Copy')
• copyCommand('Clipboard')
• execCommand('Copy')
• execClipboard('Copy')
65. Which of the following code snippets trims whitespace from the beginning and end of the given string str?
Answers:
• str.replace(/^\s+|\s+$/g, '');
• str.replace(/^\s+/,'');
• str.replace(/\s+$/,'');
• str.replace(/\s+/g,' ');
66. What is the difference between call() and apply()?
Answers:
• The call() function accepts an argument list of a function, while the apply() function accepts a single array of arguments.
• The apply() function accepts an argument list of a function, while the call() function accepts a single array of arguments.
• The call() function accepts an object list of a function, while the apply() function accepts a single array of an object.
• The call() function accepts an object list of a function, while the apply() function accepts a single array of an object.
67. Which of the following code snippets is more efficient, and why?
<script language="JavaScript">
for(i=0;i<document.images.length;i++)
document.images[i].src="blank.gif";
</script>
<script language="JavaScript">
var theimages = document.images;
for(i=0;i<theimages.length;i++)
theimages[i].src="blank.gif"
</script>
Answers:
• Both are equally efficient.
• The first code is more efficient as it contains less code.
• The first code is more efficient as it employs object caching.
• The second code is more efficient as it employs object caching.
68. What is the meaning of obfuscation in JavaScript?
Answers:
• Obfuscation is a keyword in JavaScript.
• Making code unreadable using advanced algorithms.
• Decrypting encrypted source code using advanced algorithms.
• None of these.
69. Which of the following JavaScript Regular Expression modifiers finds one or more occurrences of a specific character in a string?
Answers:
• ?
• *
• +
• #
70. Which of the following is not a valid JavaScript operator?
Answers:
• |
• ===
• %=
• ^
71. Which of the following code snippets returns "[object object]"?
Answers:
• <script> var o = new Object(); o.toSource(); </script>
• <script> var o = new Object(); o.valueOf(); </script>
• <script> var o = new Object(); o.toString(); </script>
• <script> var o = new Object(); o.getName(); </script>
72. Which of the following can be used to invoke an iframe from a parent page?
Answers:
• window.frames
• document.getElementById
• document.getelementsbyname
• document.getelementsbyclassname
73. Select the following function that shuffles an array?
Answers:
• function shuffle(array) { var tmp, current, top = array.length; if(top) while(--top) { current = Math.floor(Math.random() * (top + 1)); tmp = array[current]; array[current] = array[top]; array[top] = tmp; } return array; }
• function shuffle(array) { return array.sort(function(a,b) { return (a-b); }); }
• function shuffle(array) { var results = new Array(); var sorted_arr = array.sort(); for (var i = 0; i < array.length - 1; i++) { if (sorted_arr[i + 1] == sorted_arr[i]) { results.push(sorted_arr[i]); } } return results; }
• function shuffle(array) { for (var tmp, cur, top=array.length; top--;){ cur = (Math.random() * (top + 1)) << 0; tmp = array[cur]; array[cur] = array[top]; array[top] = tmp; } return array.sort(); }
74. Which of the following code snippets removes objects from an associative array?
Answers:
• delete array["propertyName"];
• array.propertyName.remove();
• array.splice(index, 1);
• array["propertyName"].remove();
75. What is the error in the statement: var charConvert = toCharCode('x');?
Answers:
• toCharCode() is a non-existent method.
• Nothing. The code will work fine.
• toCharCode only accepts numbers.
• toCharCode takes no arguments.
76. What value would JavaScript assign to an uninitialized variable?
Answers:
• NaN
• null
• undefined
• false
77. What does the following JavaScript code do?
contains(a, obj) {
for (var i = 0; i < a.length; i++) {
if (a[i] === obj) {
return true;
}
}
return false;
}
Answers:
• It calculates an array's length.
• It compares 'a' and 'obj' in an array.
• The code will cause an error.
• It checks if an array contains 'obj'.
78. If an image is placed styled with z-index=-1 and a text paragraph is overlapped with it, which one will be displayed on top?
Answers:
• The paragraph.
• The image.
• It depends on other rules.
79. Which of the following code snippets gets an image's dimensions (height & width) correctly?
Answers:
• var img = document.getElementById('imageid'); var width = img.clientWidth; var height = img.clientHeight;
• var img = document.getElementById('imageid'); var width = img.width; var height = img.height;
• var img = document.getElementById('imageid'); var width = img.getAttribute('width'); var height = img.getAttribute('height');
• var img=document.getElementById("imageid"); var width=img.offsetWidth; var height=img.offsetHeight;
80. Which of the following are correct values of variableC, and why?
<script>
variableA = [6,8];
variableB =[7,9];
variableC = variableA + variableB;
</script>
Answers:
• 6, 7, 8 and 9. The + operator is defined for arrays, and it concatenates strings, so it converts the arrays to strings.
• 6, 15 and 9. The + operator is defined for arrays, and it concatenates numbers, so it converts the arrays to numbers.
• 6, 8, 7 and 9. The + operator is defined for arrays, and it concatenates strings, so it converts the arrays to strings.
• 6, 87 and 9. The + operator is not defined for arrays, and it concatenates strings, so it converts the arrays to strings.
81. The following are the samples for getting a selected value in the from a dropdown list:
<select id="ddlViewBy">
<option value="1">test1</option>
<option value="2" selected="selected">test2</option>
<option value="3">test3</option>
</select>
Which code block is correct?
Answers:
• var e = document.getElementById("ddlViewBy"); var strUser = e.options[e.selectedIndex].text;
• var e = document.getElementById("ddlViewBy"); var strUser = e.options[e.selectedIndex].value;
• var e = document.getElementByName("ddlViewBy"); var strUser = e.options[e.selectedIndex].text;
• var e = document.getElementByName("ddlViewBy"); var strUser = e.options[e.selectedIndex].value;
82. var profits=2489.8237
Which of the following code(s) produces the following output?
output : 2489.824
Answers:
• profits.toFixed(4)
• profits.toFixed(3)
• profits.formatDollar(3)
• profits.nuberFormat(3)
83. A form contains two fields named id1 and id2. How can you copy the value of the id2 field to id1?
Answers:
• document.forms[0].id1.value=document.forms[0].id2.value
• document.forms[0].id2.value=document.forms[0].id1.value
• document.id1.value=document.id2.value
• document.id2.value=document.id1.value
84. Which of the following code snippets will toggle a div element's background color?
<button id="toggle">Toggle</button>
<div id="terd">Change Background Color.</div>
Answers:
• <script> var button = document.getElementById('toggle'); button.click = function() { terd.style.backgroundColor = terd.style.backgroundColor == 'blue' ? 'red' : 'blue'; }; </script>
• <script> var button = document.getElementById('toggle'); button.ready = function() { terd.style.backgroundColor = terd.style.backgroundColor == 'blue' ? 'red' : 'blue'; }; </script>
• <script> var button = document.getElementById('toggle'); button.focus = function() { terd.style.backgroundColor = terd.style.backgroundColor == 'blue' ? 'red' : 'blue'; }; </script>
• <script> var button = document.getElementById('toggle'); button.onclick = function() { terd.style.backgroundColor = terd.style.backgroundColor == 'blue' ? 'red' : 'blue'; }; </script>
85. How can the user's previously navigated page be determined using JavaScript?
Answers:
• It is not possible in JavaScript. This can be done only through server-side scripting.
• Using the document.referrer property
• Using the window object
• None of these
86. Which of the following is not a valid method for looping an array?
Answers:
• var a= [1,2]; for (var i = 0; i < a.length; i++) { alert(a[i]); }
• var a= [1,2]; a.forEach( function(item) { alert(item); })
• var a= [1,2]; a.map( function(item) { alert(item); })
• var a= [1,2]; a.loop( function(item) { alert(item); })
87. Which of the following correctly sets a class for an element?
Answers:
• document.getElementById(elementId).className = "Someclass";
• document.getElementById(elementId).setAttribute("className", "Someclass");
• document.getElementById(elementId).class = "Someclass";
• document.getElementById(elementId).style = "Someclass";
88. An HTML form contains 10 checkboxes all named "chkItems". Which JavaScript function can be used for checking all the checkboxes together?
Answers:
• function CheckAll() { for (z = 0; z < document.forms.chkItems.length; z++) { document.forms.chkItems[z].checked=true } }
• function CheckAll() { for (z = 0; z < document.forms[0].chkItems.length; z++) { document.forms[0].chkItems[z].checked=true } }
• function CheckAll() { for (z = 0; z < document.forms[0].chkItems.length; z++) { document.forms[0].chkItems.list[z].checked=true } }
• function CheckAll() { for (z = 0; z < document.forms[0].chkItems.length; z++) { document.forms[0].chkItems.list[z].checked=false } }
15 NOT Answered Yet Test Questions:
(hold on, will be updated soon)89. What is the output of the following code?
var a = 'A'.charCodeAt(0) + 5;
var b = 'c'.charCodeAt(0) + 1;
var c = 0;
for (var i = 0; i < 10; i++) {
c = c + (a+b % 2);
}
alert(c);
Answers:
• 700
• 60
• 0
• 760
90.
Which of the following choices will change the source of the image to "image2.gif" when a user clicks on the image?
Answers:
• img id="imageID" src="image1.gif" width="50" height="60" onmousedown="changeimg(image1.gif)" onmouseup="changeimg(image2.gif)"
• img id="imageID" src="image1.gif" width="50" height="60" onmouseclick="changeimg(image2.gif)" onmouseup="changeimg(image1.gif)"
• img id="imageID" src="image2.gif" width="50" height="60" onmousedown="changeimg(image1.gif)" onmouseup="changeimg(image2.gif)"
• img id="imageID" src="image2.gif" width="50" height="60" onmousedown="changeimg(image2.gif)" onmouseup="changeimg(image1.gif)"
• img id="imageID" src="image1.gif" width="50" height="60" onmousedown="changeimg('image2.gif')" onmouseup="changeimg('image1.gif')"
91. Which of the following is/are true regarding JavaScript and multi-threading/concurrency?
Answers:
• JavaScript is single-threaded, forcing asynchronous events to a queue to wait for execution.
• JavaScript is multi-threaded, and behaves in a synchronous manner.
• JavaScript can be single or multi-threaded, depending on the browser's capabilities.
• None of these.
92. Which of the following is not a valid Date Object method in JavaScript?
Answers:
• parse()
• setDay()
• setTime()
• valueOf()
93.
Consider the following JavaScript function to change the color of the text box named txtName:
function color(col) { document.forms[0].txtName.style.background=col }
Which of the following will change the color of the text box to green, as long as the user is pressing a key?
Answers:
• input type="text" onkeydown="color('white')" onkeyup="color('green')" name="txtName"
• input type="text" onkeydown="color('green')" onkeyup="color('white')" name="txtName"
• input type="text" onkeydown="color('green')" name="txtName"
• input type="text" onkeydown="color('white')" name="txtName"
• input type="text" onkeypress="color('green')" onkeyup="color('white')" name="txtName"
94.
Which of the following statements are true regarding the code below?
<script>
alert("foo" === new String("foo")); // output false
</script>
Answers:
• The "===" operator always returns false.
• The "===" operator returns true only if they refer to the same object (comparing by reference) and if both the primitive and the object have the same value.
• The "===" operator returns true only if the object (comparing by reference) and the primitive have the same value.
• The "===" operator does not work for objects.
95. Consider the following code snippet:
var myJSONObject =
{"ircEvent": "PRIVMSG", "method": "newURI", "regex": "^http://.*"};
What is the best way to remove the property 'regex', so the result would be this code snippet?
myJSONObject ==
{"ircEvent": "PRIVMSG", "method": "newURI"};
Answers:
• myJSONObject.regex.delete;
• myJSONObject.regex.remove;
• delete myJSONObject.regex;
• remove myJSONObject.regex;
96. Which of the following is the best way to show both single and double quotes in the same sentence?
Answers:
• alert("It's "+'"game"'+" time.");
• alert('It\'s \"game\" time.');
• alert('It\'\s "game" time.');
• alert('It\'s "game" time.');
97. Which of the following statements is true regarding importing JavaScript files inside of other JavaScript files?
Answers:
• There is no import/include/require keyword in JavaScript, but there ways to import JS files inside of other JS files.
• There is an import keyword in JavaScript, which allows importing JS files inside of other JS files.
• There is no option to do so in JavaScript.
98. Which of the following shortcuts can be used for writing multiple document.write statements?
Answers:
• for(document){}
• with(document) {}
• withThis(document){}
• None of these
99. In JavaScript, the encodeURI() function is used to encode special characters. Which of the following special characters is/are an exception to that rule?
A. ??
B. ???
C. @
D. $
Answers:
• A
• B
• C
• D
• A and B
• C and D
100. Consider the following code:
<form>
<textarea id="foo" name="foo"></textarea>
</form>
Which of the following is the best method to get the line number of the form's text area?
Answers:
• <script> foo.value.split(/\r\n\|\r\|\n/g); </script>
• <script> foo.value.split(/\r\/n\|\r\|\n/g); </script>
• <script> foo.value.split(/\rn\|\r\|\n/g); </script>
• <script> foo.value.split(/\r\n|\r|\n/g); </script>
101. Which of the following code snippets shows an alert for an empty string?
var a = "";
Answers:
• If(a){ alert(???This is empty string???);}
• If(a == NUL){ alert(???This is empty string???);}
• If(!a){ alert(???This is empty string???);}
• If(a.empty){ alert(???This is empty string???);}
102. Consider the following code:
var setter=new Object()
setter.color="blue"
How would you delete the color property of the variable seter?
Answers:
• setter.color delete;
• delete setter.color
• delete(setter.color)
• setter.color.delete
103. Is the following statement regarding expression closures in JavaScript true or false?
The syntax function(x) {return x*x;} can be written as function(x) x*x.
Answers:
• True
• False
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