The **`length` property** of a function denotes the `number` of arguments a function expects. 

The returned number excludes the #key# rest parameter: which accepts an indefinite number of arguments as an array #key# and default value parameter.

# Example 1

function test(a, b, c){
  console.log("hi")
}
console.log("The number argument expected by test function is ")
console.log(test.length);

In the code above, we created a `test` function with `3` arguments, `(a,b,c)`. We checked the number of arguments expected by the `test` function through the `length` property of the `function` object. The `test.length` will return `3` because it expects `3` arguments.

# Example 2 

function test(a, b = 10, ...c) {
  console.log(a, b,  c);
}

console.log("The number argument expected by test function is ")
console.log(test.length);


In the code above, we created a `test` function with `3` arguments, `(a, b=10, ...c)`, in which `b` is the *default parameter* and `c` is the *rest parameter*. 

The `length` property of the `function` object doesn't include the `rest` and `default` parameters, so the `test.length` will return `1`.

# Difference between `arguments.length` and `function.length`

The **`arguments.length`** denotes the number of arguments *actually passed* to the function, whereas the **`function.length`** denotes the number of arguments *expected by* the function. 

What is function.length in JavaScript?

The function length property shows the number of expected arguments, excluding rest and default parameters.

What is function.length in JavaScript?

Example 1

Example 2

Difference between arguments.length and function.length

Difference between `arguments.length` and `function.length`