Difference between == and === in JavaScript [duplicate]

Difference between == and === in JavaScript [duplicate]

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

What is the difference between == and === in JavaScript? I have also seen != and !== operators. Are there more such operators?


Solution 1:

=== and !== are strict comparison operators:

JavaScript has both strict and
type-converting equality comparison.
For strict equality the objects being
compared must have the same type and:

  • Two strings are strictly equal when they have the same sequence of
    characters, same length, and same
    characters in corresponding positions.
  • Two numbers are strictly equal when they are numerically equal (have
    the same number value). NaN is not
    equal to anything, including NaN.
    Positive and negative zeros are equal
    to one another.
  • Two Boolean operands are strictly equal if both are true or
    both are false.
  • Two objects are strictly equal if they refer to the same Object.
  • Null and Undefined types are == (but not ===). [I.e. (Null==Undefined) is true but (Null===Undefined) is false]

Comparison Operators – MDC

Solution 2:

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, automatic type conversion for value only
1 === "1"    // false, because they are of a different type
null == undefined // true
null === undefined // false
'0' == false // true
'0' === false // false