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