Inequality (!=) - JavaScript | MDN (original) (raw)

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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.

Try it

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

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

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

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

Syntax

Description

The inequality operator checks whether its operands are not equal. It is the negation of the equalityoperator so the following two lines will always give the same result:

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:

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

Examples

Comparison with no type conversion

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

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

Comparison with type conversion

"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

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

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

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

Specifications

Browser compatibility

See also