JavaScript(JS) function method - length

The length property is a built-in property in JavaScript that is available on all function objects. It returns the number of named parameters that a function expects to receive. This includes all parameters before the first one with a default value.

Here's an example that demonstrates how to use the length property:

function exampleFunction(a, b, c, d = 0, e = 1) {
  // function body
}

console.log(exampleFunction.length); // Output: 4

In the example above, the exampleFunction function has four named parameters a, b, c, and d. The last two parameters d and e have default values and are not included in the length property count.

Note that the length property does not include any rest parameters (...args), since they can be any number of arguments. It also does not include any parameters that are provided through the arguments object.

The length property is useful for functions that need to handle a specific number of arguments or for functions that are expected to have a certain number of parameters. For example, some libraries and frameworks use the length property to check the number of arguments passed to a function and perform different actions depending on the number of arguments.