Avoid use of
== and != JS-0050
Anti-pattern
5 months ago
—
5 months old
Expected '===' and instead saw '=='
1/*! jQuery v3.6.0 | (c) OpenJS Foundation and other contributors | jquery.org/license */
2!(function (e, t) {
3 "use strict";
4 "object" == typeof module && "object" == typeof module.exports 5 ? (module.exports = e.document
6 ? t(e, !0)
7 : function (e) {Expected '===' and instead saw '=='
1/*! jQuery v3.6.0 | (c) OpenJS Foundation and other contributors | jquery.org/license */
2!(function (e, t) {
3 "use strict";
4 "object" == typeof module && "object" == typeof module.exports 5 ? (module.exports = e.document
6 ? t(e, !0)
7 : function (e) {Expected '!==' and instead saw '!='
10 return t(e);
11 })
12 : t(e);
13})("undefined" != typeof window ? window : this, function (C, e) { 14 "use strict";
15 var t = [],
16 r = Object.getPrototypeOf,Expected '===' and instead saw '=='
32 y = {},
33 m = function (e) {
34 return (
35 "function" == typeof e && 36 "number" != typeof e.nodeType &&
37 "function" != typeof e.item
38 );Expected '!==' and instead saw '!='
33 m = function (e) {
34 return (
35 "function" == typeof e &&
36 "number" != typeof e.nodeType && 37 "function" != typeof e.item
38 );
39 },
Description
It is considered good practice to use the type-safe equality operators === and !== instead of their regular counterparts == and !=.
The strict equality operators (=== and !==) use the strict equality comparison algorithm to compare two operands.
- If the operands are of different types, return
false. - If both operands are objects, return
trueonly if they refer to the same object. - If both operands are
nullor both operands areundefined, returntrue. - If either operand is
NaN, returnfalse. - Otherwise, compare the two operand's values:
- Numbers must have the same numeric values.
+0and-0are considered to be the same value. - Strings must have the same characters in the same order.
- Booleans must be both
trueor bothfalse.
- Numbers must have the same numeric values.
The most notable difference between this operator and the equality (==) operator is that if the operands are of different types, the == operator attempts to convert them to the same type before comparing.
Bad Practice
a == b
foo == true
bananas != 1
value == undefined
typeof foo == 'undefined'
'hello' != 'world'
0 == 0
true == true
foo == null
Recommended
a === b
foo === true
bananas !== 1
value === undefined
typeof foo === 'undefined'
'hello' !== 'world'
0 === 0
true === true
foo === null