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# Math.imul

## Math.imul

The `Math.imul()` function returns the result of the C-like 32-bit multiplication of the two parameters.

## Syntax

``Math.imul(a, b)``

`a`
First number.
`b`
Second number.

## Description

`Math.imul()` allows for fast 32-bit integer multiplication with C-like semantics. This feature is useful for projects like Emscripten. Because `imul()` is a static method of `Math`, you always use it as `Math.imul()`, rather than as a method of a `Math` object you created (`Math` is not a constructor).

## Examples

### Using `Math.imul()`

```Math.imul(2, 4);          // 8
Math.imul(-1, 8);         // -8
Math.imul(-2, -2);        // 4
Math.imul(0xffffffff, 5); // -5
Math.imul(0xfffffffe, 5); // -10
```

## Polyfill

This can be emulated with the following function:

```Math.imul = Math.imul || function(a, b) {
var ah = (a >>> 16) & 0xffff;
var al = a & 0xffff;
var bh = (b >>> 16) & 0xffff;
var bl = b & 0xffff;
// the shift by 0 fixes the sign on the high part
// the final |0 converts the unsigned value into a signed value
return ((al * bl) + (((ah * bl + al * bh) << 16) >>> 0)|0);
};
```