Cracking JavaScript,HTML and CSS Interviews (Part-1)

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JavaScript:-

1) what are the Data types in JavaScript?
2) What will be the value of a?

Scenario1:
function fn(){
alert(a);
a = 10;
alert(a);
}
alert(a);
fn();
alert(a);

Scenario 2:
function fn(){
alert(a);
var  a = 10;
alert(a);
};
alert(a);
a=20;
fn();
alert(a);

3) What will be the value of a and b?
Scenario 1:
var a =10;
var b = a;
 a= null;

Scenario 2:
var obj ={};
obj.a = 10;
obj.b= obj.a;
obj.a =null;

4) What are the different methods to call a function in JavaScript?
5) What is the difference between function.call() and function.apply()?
6) What is event propagation?
7) What is the scope of variables in JavaScript?
8) Explain hoisting?
9) Difference between === and == ?
10) What will be value of  “” == 0?
11) Why we implement “use strict”?

HTML:-
1) If !DOCTYPE is not mentioned, will the page render?
2) What are the New form elements in HTML5.
3) Local Storage
a) Is local storage domain specific?
b) Can we access local storage in different browsers if a website using local storage is open only on one browser?
c) What is the scope of session storage?


CSS:-

1) What is positioning? Explain along with examples?
2) Difference between display:none; , visibility:hidden; , overflow:hidden;? Where should we use it?