The Math.log() function returns the natural logarithm (base e) of a number, that is
The JavaScript Math.log() function is equivalent to ln(x) in mathematics.
Math.log()
Try it
Syntax
Math.log(x)
Parameters
-
x -
A number.
Return value
Description
If the value of x is 0, the return value is always -Infinity.
If the value of x is negative, the return value is always NaN.
Because log() is a static method of Math, you always use it as Math.log(), rather than as a method of a Math object you created (Math is not a constructor).
If you need the natural log of 2 or 10, use the constants Math.LN2 or Math.LN10. If you need a logarithm to base 2 or 10, use Math.log2() or Math.log10(). If you need a logarithm to other bases, use Math.log(x) / Math.log(otherBase) as in the example below; you might want to precalculate 1 / Math.log(otherBase).
Examples
Using Math.log()
Math.log(-1); // NaN, out of range Math.log(0); // -Infinity Math.log(1); // 0 Math.log(10); // 2.302585092994046
Using Math.log() with a different base
The following function returns the logarithm of y with base x (ie.
):
function getBaseLog(x, y) { return Math.log(y) / Math.log(x); }
If you run getBaseLog(10, 1000) it returns 2.9999999999999996 due to floating-point rounding, which is very close to the actual answer of 3.
Specifications
| Specification |
|---|
| ECMAScript Language Specification # sec-math.log |
Browser compatibility
| Desktop | Mobile | Server | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Chrome | Edge | Firefox | Internet Explorer | Opera | Safari | WebView Android | Chrome Android | Firefox for Android | Opera Android | Safari on IOS | Samsung Internet | Deno | Node.js | |
log |
1
|
12
|
1
|
3
|
3
|
1
|
1
|
18
|
4
|
10.1
|
1
|
1.0
|
1.0
|
0.10.0
|
See also
© 2005–2022 MDN contributors.
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Math/log
