Is it necessary to use === to compare strings in Javascript or is == enough? [duplicate]

Question

Possible Duplicate:
JavaScript === vs == : Does it matter which “equal” operator I use?

I can understand why === is necessary when comparing numbers, booleans, empty strings, etc, due to unexpected type conversions e.g.

var foo = 1; 
var bar = true; 
// bar == foo => true
// bar === foo => false

But can == ever introduce a bug when comparing a variable to a non-empty string literal? Is it more efficient to use == over === in this case?

Answer 1

This has been asked here a lot so I'll just let a better poster then myself answer.

Take a look here: http://longgoldenears.blogspot.com/2007/09/triple-equals-in-javascript.html

The 3 equal signs mean "equality without type coercion". Using the triple equals, the values must be equal in type as well.

0==false   // true
0===false  // false, because they are of a different type
1=="1"     // true, auto type coercion
1==="1"    // false, because they are of a different type

source Difference between == and === in JavaScript

Answer 2

It is a good practice to always use the identity operators (!== and ===) and perform type coercion manually only when you need to (e.g. Boolean(someVar) or Number(someVar)).

A fun fiddle.