The !== operator checks whether its two operands are not equal, returning a Boolean result. Unlike the inequality operator, the strict inequality operator always considers operands of different types to be different.
Strict inequality (!==)
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Syntax
js
x !== y
Description
The strict inequality operator checks whether its operands are not equal. It is the negation of the strict equality operator so the following two lines will always give the same result:
js
x !== y;
!(x === y);
For details of the comparison algorithm, see the page for the strict equality operator.
Like the strict equality operator, the strict inequality operator will always consider operands of different types to be different:
js
3 !== "3"; // true
Examples
Comparing operands of the same type
js
"hello" !== "hello"; // false
"hello" !== "hola"; // true
3 !== 3; // false
3 !== 4; // true
true !== true; // false
true !== false; // true
null !== null; // false
Comparing operands of different types
js
"3" !== 3; // true
true !== 1; // true
null !== undefined; // true
Comparing objects
js
const object1 = {
key: "value",
};
const object2 = {
key: "value",
};
console.log(object1 !== object2); // true
console.log(object1 !== object1); // false
Specifications
Browser compatibility
| Desktop | Mobile | Server | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Chrome | Edge | Firefox | Opera | Safari | Chrome Android | Firefox for Android | Opera Android | Safari on IOS | Samsung Internet | WebView Android | Deno | Node.js | ||
Strict_inequality |
1 | 12 | 1 | 4 | 1 | 18 | 4 | 10.1 | 1 | 1.0 | 4.4 | 1.0 | 0.10.0 | |
See also
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Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Strict_inequality