Inequality (!=)

The inequality (!=) operator checks whether its two operands are not equal, returning a Boolean result. Unlike the strict inequality operator, it attempts to convert and compare operands that are of different types.

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Syntax

js

x != y

Description

The inequality operator checks whether its operands are not equal. It is the negation of the 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 equality operator.

Like the equality operator, the inequality operator will attempt to convert and compare operands of different types:

js

3 != "3"; // false

To prevent this, and require that different types are considered to be different, use the strict inequality operator instead:

js

3 !== "3"; // true

Examples

Comparison with no type conversion

js

1 != 2; // true
"hello" != "hola"; // true

1 != 1; // false
"hello" != "hello"; // false

Comparison with type conversion

js

"1" != 1; // false
1 != "1"; // false
0 != false; // false
0 != null; // true
0 != undefined; // true
0 != !!null; // false, look at Logical NOT operator
0 != !!undefined; // false, look at Logical NOT operator
null != undefined; // false

const number1 = new Number(3);
const number2 = new Number(3);
number1 != 3; // false
number1 != number2; // true

Comparison of objects

js

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

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

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

Specifications

Specification
ECMAScript Language Specification
# sec-equality-operators

Browser compatibility

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See also