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title: arguments.length
short-title: length
slug: Web/JavaScript/Reference/Functions/arguments/length
page-type: javascript-instance-data-property
browser-compat: javascript.functions.arguments.length
sidebar: jssidebar
---
The **`arguments.length`** data property contains the number of arguments passed to the function.
## Value
A non-negative integer.
{{js_property_attributes(1, 0, 1)}}
## Description
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 {{jsxref("Function.prototype.length")}}). For example, for the function below:
```js
function func1(a, b, c) {
console.log(arguments.length);
}
```
`func1.length` returns `3`, because `func1` declares three formal parameters. However, `func1(1, 2, 3, 4, 5)` logs `5`, because `func1` was called with five arguments. Similarly, `func1(1)` logs `1`, because `func1` was called with one argument.
## Examples
### Using arguments.length
In this example, we define a function that can add two or more numbers together.
```js
function adder(base /*, num1, …, numN */) {
base = Number(base);
for (let i = 1; i < arguments.length; i++) {
base += Number(arguments[i]);
}
return base;
}
```
## Specifications
{{Specifications}}
## Browser compatibility
{{Compat}}
## See also
- [Functions](/en-US/docs/Web/JavaScript/Guide/Functions) guide
- [Functions](/en-US/docs/Web/JavaScript/Reference/Functions)
- {{jsxref("Functions/arguments", "arguments")}}
- [`Function`: `length`](/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/length)
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