JQuery Basic Interview Questions Part-3

What’s relationship between JavaScript and ECMAScript?- ECMAScript is yet another name for
 JavaScript (other names include LiveScript). The current JavaScript that you see supported in browsers is ECMAScript revision 3.
What are JavaScript types?
Number, String, Boolean, Function, Object, Null, Undefined.
How do you convert numbers between different bases in JavaScript?
Use the parseInt() function, that takes a string as the first parameter, and the base as a second parameter. So to convert hexadecimal 3F to decimal, use parseInt ("3F", 16);
What does isNaN function do?
Return true if the argument is not a number.
What is negative infinity?
It’s a number in JavaScript, derived by dividing negative number by zero.
What boolean operators does JavaScript support?
&&, || and !
 What does "1"+2+4 evaluate to?
Since 1 is a string, everything is a string, so the result is 124.
How about 2+5+"8"?
Since 2 and 5 are integers, this is number arithmetic, since 8 is a string, it’s concatenation, so 78 is the result.
What looping structures are there in JavaScript?
for, while, do-while loops, but no foreach.
How do you create a new object in JavaScript?
var obj = new Object(); or var obj = {};
How do you assign object properties?
obj["age"] = 17 or obj.age = 17.
 What’s a way to append a value to an array?
arr[arr.length] = value;
What is this keyword?
It refers to the current object.
Is jQuery a library for client scripting or server scripting?
Client scripting
Is jQuery a W3C standard?
No
What are jQuery Selectors?
Selectors are used in jQuery to find out DOM elements. Selectors can find the elements via ID, CSS, Element name and hierarchical position of the element.
The jQuery html() method works for both HTML and XML documents?
It only works for HTML.
Which sign does jQuery use as a shortcut for jQuery?
$(dollar) sign.
What does $("div") will select?

It will select all the div element in the page.
What does $("div.parent") will select?

All the div element with parent class.
What is the name of jQuery method used for an asynchronous HTTP request?
jQuery.ajax()