JavaScript Function Arguments

In JavaScript, we don’t have any method to check our parameters and arguments.

Earlier tutorial, We have learned that functions can have parameters; such like –

functionName(parameter1, parameter2, parameter3) {
    code to be executed
}

but suppose that we missed one parameter or arguments like –

function msg(name, msg) {

    if (msg === undefined) {
          msg = "Welcome to Javascript";
    } 
}

Here you are handling the missing case. But how to manage if we have too many arguments?
So for that condition, we have a special object; arguments object

How it works

function sum () {
	
	for (var i = 0, sum = 0; i < arguments.length; i++) {
		sum += arguments[i];
	}

	return sum;
}

console.info(sum(1, 2, 3, 4, 5)); // 15

Now you can see arguments works like an array. But it’s not an array. It has only length property. So be careful when you are using arguments.

function isArray () { 

	return Array.isArray(arguments);
}

console.info(Array.isArray()); // false

So If we want to use this like an array so we need to follow these steps –

var args = Array.prototype.slice.call(arguments);
var args = [].slice.call(arguments);

How to use

function isArray () {
   var args = Array.prototype.slice.call(arguments);
   var args = [].slice.call(arguments);

   return Array.isArray(args);
}

console.info(isArray()); // true