What is equality comparison in javascript

Equality comparison refers to comparing whether the values ​​​​of two expressions (or operands) are equal. The comparison methods are: 1. Use the "==" operator, the syntax "a==b"; 2. Use the "===" operator, the syntax is "a===b"; 3. Use the "Object.is()" method, the syntax is "Object.is(a, b)".

The operating environment of this tutorial: windows7 system, javascript version 1.8.5, Dell G3 computer.

Equality comparison in javascript

In javascript, equality comparison refers to comparing two expressions (or operands) Whether the values ​​are equal.

We all know that JavaScript is loosely typed, and in some cases, when using == to do equality comparison, it will give you unexpected results. This is because when using == to do equivalent comparison, JavaScript will perform an implicit cast on the two compared values.

0 == ' ' //true
null == undefined //true
[1] == true //true

So JavaScript also provides us with three equal sign operators===, which is more strict and does not force conversion of comparison values, but is practical=== Sometimes comparison is not the best solution:

NaN === NaN //false

The good news is that there is a new better and more accurate method in ES6Object.is(), It has the same functionality as ===, and performs well in some special cases:

Object.is(0 , ' '); //false
Object.is(null, undefined); //false
Object.is([1], true); //false
Object.is(NaN, NaN); //true

The picture below details ==,## Similarities and differences between #=== and Object.is() equivalent price comparison:

[Related recommendations:

javascript learning tutorial 】

The above is the detailed content of What is equality comparison in javascript. For more information, please follow other related articles on the PHP Chinese website!