Strict inequality (!==)

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This feature is well established and works across many devices and browser versions. Its been available across browsers since July 2015.

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The strict inequality (!==) 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.

Try it

console.log(1 !== 1);
// Expected output: false

console.log("hello" !== "hello");
// Expected output: false

console.log("1" !== 1);
// Expected output: true

console.log(0 !== false);
// Expected output: true

Syntax

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:

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:

3 !== "3"; // true

Examples

Comparing operands of the same type

"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

"3" !== 3; // true
true !== 1; // true
null !== undefined; // true

Comparing objects

const object1 = {
  key: "value",
};

const object2 = {
  key: "value",
};

console.log(object1 !== object2); // true
console.log(object1 !== object1); // false