What is exactly the meaning of "===" in javascript?

 

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Javascript === vs ==

What's the diff between "===" and "==" ? Thanks!

'===' means equality without type coersion. In other words, if using the triple equals, the values must be equal in type as well.

eg 

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

Source: http://longgoldenears.blogspot.com/2007/09/triple-equals-in-javascript.html

Ripped from my blog: keithdonegan.com

The Equality Operator (==)

The equality operator (==) checks whether two operands are the same and returns true if they are the same and false if they are different.

The Identity Operator (===)

The identity operator checks whether two operands are “identical”.

These rules determine whether two values are identical:

  • They have to have the same type.
  • If number values have the same value they are identical, unless one or both are NaN.
  • If string values have the same value they are identical, unless the strings differ in length or content.
  • If both values refer to the same object, array or function they are identical.
  • If both values are null or undefined they are identical.

    • The === operator means "is exactly equal to," matching by both value and data type.

    The == operator means "is equal to," matching by value only.

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