JavaScript arguments object

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The JavaScript arguments object is a local variable available within all functions. It contains all the function parameters that are passed to the function and can be indexed like an array. The length property of the arguments object returns the number of arguments passed to the function.



JavaScript arguments object example :

function printArguments()

{

    document.write("Number of arguments = " + arguments.length + "<br/>")

    for (var i = 0; i < arguments.length; i++)

    {

        document.write("Argument " + i + " = " + arguments[i] + "<br/>");

    }

    document.write("<br/>");

}

printArguments();

printArguments("A", "B");

printArguments(10, 20, 30);

Output : 


Is it possible to pass variable number of arguments to a JavaScript function
Yes, you can pass as many arguments as you want to any javascript function. All the parameters will be stored in the arguments object.

function addNumbers()

{

    var sum = 0;

    document.write("Count of numbers = " + arguments.length + "<br/>")

    for (var i = 0; i < arguments.length; i++)

    {

        sum = sum + arguments[i];

    }

    document.write("Sum of numbers = " + sum);

    document.write("<br/><br/>");

}

addNumbers();

addNumbers(10, 20, 30);

Output : 


The arguments object is available only inside a function body. Attempting to access the arguments object outside a function results in 'arguments' is undefined error. Though you can index the arguments object like an array, it is not an array. It does not have any Array properties except length. For example it does not have the sort() method, that the array object has. However, you can convert the arguments object to an array.

Converting JavaScript arguments object to an array
function numbers() 
{
    var argsArray = Array.prototype.slice.call(arguments);
    argsArray.sort();
    document.write(argsArray);
}

numbers(50, 20, 40);

Output : 20, 40, 50

Converting JavaScript arguments object to an array using array literals
function numbers() 
{
    var argsArray = [].slice.call(arguments);
    argsArray.sort();
    document.write(argsArray);
}

numbers(50, 20, 40);

Output : 20, 40, 50