Inequality (!=) - JavaScript 编辑

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

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:

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:

3 != "3"; // false

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

3 !== "3"; // true

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"};

object1 != object2 // true
object2 != object2 // false

Specifications

Browser compatibility

BCD tables only load in the browser

See also

• Equality operator
• Strict equality operator
• Strict inequality operator