Javascript viva questions
•Download as DOCX, PDF•
1 like•1,173 views
Javascript viva questions
![Ans:ex:-
Code
Collapse |CopyCode
<!DOCTYPE html>
<html>
<body>
Full name:<inputtype="text"id="txtFullName"
name="FirstName"value="VikasAhlawat">
</body>
</html>
There are followingwaystoaccessthe value of the above textbox:
Copy Code
var name = document.getElementById('txtFullName').value;
alert(name);
or:
we can use the oldway:
Copy Code
document.forms[0].mybutton.
var name = document.forms[0].FirstName.value;
alert(name);
Note:Thisusesthe "name"attribute of the elementtolocate it.
9) What are the ways of making comments inJavaScript?
Ans:
Collapse |CopyCode
// isusedfor line comments
ex:- varx=10; //commenttext
/*
*/ isusedforblockcomments
ex:-
Collapse |CopyCode
var x= 10; /* this is
blockcommentexample.*/
10) How will you get the Checkboxstatus whetherit is checkedor not?
Ans:
Collapse |CopyCode
var status= document.getElementById('checkbox1').checked;
alert(status);
will returntrue or false.
11) How to create arrays in JavaScript?
Ans:There are twowaysto create array inJavaScriptlike otherlanguages:](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
Recommended
More Related Content
What's hot
What's hot (20)
Similar to Javascript viva questions
Similar to Javascript viva questions (20)
More from Vipul Naik
Recently uploaded
Recently uploaded (20)
Javascript viva questions
- 1. Javascript Viva Questions 1) What is JavaScript? Ans:JavaScriptisascriptinglanguage mostoftenusedforclient-side webdevelopment. 2) What is the difference betweenJavaScriptand Jscript? Ans:BothJavaScriptandJscriptare almostsimilar.JavaScriptwasdevelopedbyNetscape.Microsoft reverse engineeredJavascriptandcalleditJScript. 3) How do we add JavaScript onto a webpage? Ans:There are several wayforaddingJavaScriptona webpage,butthere are twoways whichare commonlyusedbydevelopers If your scriptcode isveryshort andonlyfor single page,thenfollowingwaysare the best: a) You can place <script type="text/javascript">taginside the <head>element. Code Collapse |Copy Code <head> <title>Page Title</title> <script language="JavaScript"type="text/javascript"> var name = "VikasAhlawta" alert(name); </script> </head> b) If yourscript code is verylarge,thenyoucan make a JavaScriptfile andaddits pathin the followingway: Code Collapse |CopyCode <head> <title>Page Title</title> <script type="text/javascript"src="myjavascript.js"></script> </head> 4) Is JavaScript case sensitive? Ans:Yes! A functiongetElementByIdisnotthe same asgetElementbyID. 5) What are the typesused in JavaScript? Ans:String,Number,Boolean,Function,Object,Null,Undefined. 6) What are the booleanoperators supportedby JavaScript? And Operator: && Or Operator:|| NotOperator:! 7) What is the difference between“==” and“===”? Ans: “==” checksequalityonly, “===” checksforequalityaswell asthe type. 8) How to access the value of a textbox usingJavaScript?
- 2. Ans:ex:- Code Collapse |CopyCode <!DOCTYPE html> <html> <body> Full name:<inputtype="text"id="txtFullName" name="FirstName"value="VikasAhlawat"> </body> </html> There are followingwaystoaccessthe value of the above textbox: Copy Code var name = document.getElementById('txtFullName').value; alert(name); or: we can use the oldway: Copy Code document.forms[0].mybutton. var name = document.forms[0].FirstName.value; alert(name); Note:Thisusesthe "name"attribute of the elementtolocate it. 9) What are the ways of making comments inJavaScript? Ans: Collapse |CopyCode // isusedfor line comments ex:- varx=10; //commenttext /* */ isusedforblockcomments ex:- Collapse |CopyCode var x= 10; /* this is blockcommentexample.*/ 10) How will you get the Checkboxstatus whetherit is checkedor not? Ans: Collapse |CopyCode var status= document.getElementById('checkbox1').checked; alert(status); will returntrue or false. 11) How to create arrays in JavaScript? Ans:There are twowaysto create array inJavaScriptlike otherlanguages:
- 3. a) The firstway to create array Declare Array: Code Collapse |CopyCode var names= newArray(); AddElementsinArray:- names[0] = "Vikas"; names[1] = "Ashish"; names[2] = "Nikhil"; b) This isthe secondway: Collapse |CopyCode var names= newArray("Vikas","Ashish","Nikhil"); 12) If an array with name as "names" contain three elements,thenhowwill you print the third elementofthis array? Ans:Printthirdarray elementdocument.write(names[2]); Note:- Arrayindex startswith0. 13) How do you submit a form using JavaScript? Ans:Use document.forms[0].submit(); 14) What doesisNaNfunction do? Ans:It returnstrue if the argumentisnot a number. Example: Code Collapse |CopyCode document.write(isNaN("Hello")+"<br>"); document.write(isNaN("2013/06/23")+ "<br>"); document.write(isNaN(123)+"<br>"); The outputwill be: Collapse |CopyCode true true false 15) What isthe use of Math Objectin JavaScript? Ans:The mathobjectprovidesyoupropertiesandmethodsformathematical constantsand functions. ex:- Code Collapse |CopyCode var x = Math.PI; //ReturnsPI var y = Math.sqrt(16);// Returnsthe square rootof 16 var z = Math.sin(90); Returnsthe sine of 90 getElementById(“myText”).className =“anyclass”;