how to create functions with variable arguments in javascript?

Question

I want to create a function in javascript with a variable amount of arguments. The next example is how I want to call this function:

myFunction(1,2);
myFunction(1,2,3);
myFunction(1,2,3,4);
myFunction(1,2,3,4,5);
myFunction(1,2,3,4,5,6);

Anyone knows how to define this function?

@TJHeuvel I don't agree, this is not the same question... Here tlaks about number of parameters and the other about default parameters — Jean-Charles, Sep 09 '11 at 13:59
possible duplicate of [JavaScript variable number of arguments to function](http://stackoverflow.com/questions/2141520/javascript-variable-number-of-arguments-to-function) — Alexis King, Jan 21 '15 at 05:59
Possible duplicate of [Is it possible to send a variable number of arguments to a JavaScript function?](https://stackoverflow.com/questions/1959040/is-it-possible-to-send-a-variable-number-of-arguments-to-a-javascript-function) — Anderson Green, Jun 20 '17 at 17:41

score 33 · Accepted Answer · answered Sep 09 '11 at 13:52

33

You can access the arguments by their ordinal position without the need to state them in the prototype as follows:

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

myFunction(1, 2, "three");

>>1
>>2
>>three

Or if you really are passing in a set of semantically related numbers you could use an array;

function myFunction(arr) { ... }
result = myFunction([1,2,3]);

answered Sep 09 '11 at 13:52

Alex K.

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I also saw this solution in the book: "Javascript, the definitive guide". Thanks. – McSas Sep 13 '11 at 02:56

optimistanoop · Answer 2 · 2017-06-16T13:37:54.177

14

Latest update

Rest parameters are supported in all new browsers. Check here for details

The rest parameter syntax allows us to represent an indefinite number of arguments as an array, which you can pass it to other functions too.

function myFunction(...data){
  console.log(...data);
  myOtherFunction(...data);
}

myFunction(1,2,3);     //logs 1,2,3

myFunction([1,2,3]);   //logs [1,2,3]

edited Jun 16 '17 at 13:37

answered Apr 26 '17 at 09:57

optimistanoop

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Jean-Charles · Answer 3 · 2011-09-09T14:05:00.783

3

Use the 'arguments' variable like this :

function myFunction() {
    alert(arguments.length + ' arguments');
    for( var i = 0; i < arguments.length; i++ ) {
        alert(arguments[i]);
    }
 }

Call the methods as you did before

myFunction(1,2);
myFunction(1,2,3,4,5,6);

edited Sep 09 '11 at 14:05

answered Sep 09 '11 at 13:57

Jean-Charles

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score 2 · Answer 4 · answered Sep 09 '11 at 13:52

2

Just refer to the arguments array.

https://developer.mozilla.org/en/JavaScript/Reference/functions_and_function_scope/arguments

answered Sep 09 '11 at 13:52

Matthew Wilson

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score 2 · Answer 5 · answered Sep 09 '11 at 13:56

If an argument is not present, use the default. Like this...

function accident() {
    //Mandatory Arguments
    var driver = arguments[0];
    var condition = arguments[1]

    //Optional Arguments
    var blame_on = (arguments[2]) ? arguments[2] : "Irresponsible tree" ;
}

accident("Me","Drunk");

score 1 · Answer 6 · answered Jul 31 '15 at 15:22

1

As an add-on: You can assign values to the unnamed function parameters, as in (german wiki)

arguments[0] = 5;

answered Jul 31 '15 at 15:22

serv-inc

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how to create functions with variable arguments in javascript?

6 Answers6

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