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Bitwise AND assignment (&=)

Baseline Widely available

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

The bitwise AND assignment (&=) operator performs bitwise AND on the two operands and assigns the result to the left operand.

In this article

Try it

let a = 5; // 00000000000000000000000000000101 a &= 3; // 00000000000000000000000000000011 console.log(a); // 00000000000000000000000000000001 // Expected output: 1

Syntax

js
x &= y

Description

x &= y is equivalent to x = x & y, except that the expression x is only evaluated once.

Examples

Using bitwise AND assignment

js
let a = 5; // 5: 00000000000000000000000000000101 // 2: 00000000000000000000000000000010 a &= 2; // 0 let b = 5n; b &= 2n; // 0n

Specifications

Specification
ECMAScript® 2027 Language Specification
# sec-assignment-operators

Browser compatibility

Enable JavaScript to view this browser compatibility table.

See also

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  1. JavaScript
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  8. Expressions & operators
    1. Addition (+)
    2. Addition assignment (+=)
    3. Assignment (=)
    4. async function expression
    5. async function* expression
    6. await
    7. Bitwise AND (&)
    8. Bitwise AND assignment (&=)
    9. Bitwise NOT (~)
    10. Bitwise OR (|)
    11. Bitwise OR assignment (|=)
    12. Bitwise XOR (^)
    13. Bitwise XOR assignment (^=)
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    35. instanceof
    36. Left shift (<<)
    37. Left shift assignment (<<=)
    38. Less than (<)
    39. Less than or equal (<=)
    40. Logical AND (&&)
    41. Logical AND assignment (&&=)
    42. Logical NOT (!)
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    105. TypeError: can't convert x to BigInt
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    113. TypeError: cyclic object value
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  14. Misc
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    2. Execution model
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    8. Deprecated features

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