The arguments.length property contains the number of arguments passed to the function.
arguments.length
The arguments.length property provides the number of arguments actually passed to a function. This can be more or less than the defined parameter's count (see Function.length).
arguments.length
In this example we define a function that can add two or more numbers together.
function adder(base /*, n2, ... */) {
base = Number(base);
for (var i = 1; i < arguments.length; i++) {
base += Number(arguments[i]);
}
return base;
}
Note the difference between Function.length and arguments.length
| Specification | Status | Comment |
|---|---|---|
| ECMAScript 1st Edition (ECMA-262) | Standard | Initial definition. Implemented in JavaScript 1.1 |
| ECMAScript 5.1 (ECMA-262) The definition of 'Arguments Object' in that specification. | Standard | |
| ECMAScript 2015 (6th Edition, ECMA-262) The definition of 'Arguments Exotic Objects' in that specification. | Standard | |
| ECMAScript Latest Draft (ECMA-262) The definition of 'Arguments Exotic Objects' in that specification. | Draft |
| Desktop | ||||||
|---|---|---|---|---|---|---|
| Chrome | Edge | Firefox | Internet Explorer | Opera | Safari | |
| Basic support | Yes | Yes | 1 | Yes | Yes | Yes |
| Mobile | |||||||
|---|---|---|---|---|---|---|---|
| Android webview | Chrome for Android | Edge Mobile | Firefox for Android | Opera for Android | iOS Safari | Samsung Internet | |
| Basic support | Yes | Yes | Yes | 4 | Yes | Yes | Yes |
| Server | |
|---|---|
| Node.js | |
| Basic support | Yes |
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https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/arguments/length