Sets the result of a bitwise AND operation on the value of a variable and the value of an expression. The variable and the expression are treated as 32-bit integers.

## Syntax

```
result &= expression
```

## Parameters

`result`

Any variable.

`expression`

Any expression.

## Remarks

Using this operator is the same as specifying:

```
result = result & expression
```

The Bitwise AND Operator (&) looks at the binary representation of the values of `result`

and `expression`

and does a bitwise AND operation on them. The output of this operation behaves like this:

```
// 9 is 00000000000000000000000000001001
var expr1 = 9;
// 5 is 00000000000000000000000000000101
var expr2 = 5;
// 1 is 00000000000000000000000000000001
expr1 &= expr2;
document.write(expr1);
```

Any time both of the expressions have a 1 in a digit, the result has a 1 in that digit. Otherwise, the result has a 0 in that digit.

## Requirements

Supported in the following document modes: Quirks, Internet Explorer 6 standards, Internet Explorer 7 standards, Internet Explorer 8 standards, Internet Explorer 9 standards, Internet Explorer 10 standards, Internet Explorer 11 standards. Also supported in Store apps (Windows 8 and Windows Phone 8.1). See Version Information.

## See Also

Bitwise AND Operator (&)

Operator Precedence

Operator Summary (JavaScript)