arguments.length

BaselineWidely available

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

Thearguments.length data property contains the number of arguments passed to the function.

Value

A non-negative integer.

Property attributes of`arguments.length`
Writable	yes
Enumerable	no
Configurable	yes

Thearguments.length property provides the number of arguments actually passed to a function. This can be more or less than the defined parameter's count (seeFunction.prototype.length). For example, for the function below:

function func1(a, b, c) {  console.log(arguments.length);}

func1.length returns3, becausefunc1 declares three formal parameters. However,func1(1, 2, 3, 4, 5) logs5, becausefunc1 was called with five arguments. Similarly,func1(1) logs1, becausefunc1 was called with one argument.

Examples

Using arguments.length

In this example, we define a function that can add two or more numbers together.

function adder(base /*, num1, …, numN */) {  base = Number(base);  for (let i = 1; i < arguments.length; i++) {    base += Number(arguments[i]);  }  return base;}