javascript: different constructors for same type of object

Question

is it possible to have more than one constructors for a class in javascript? i.e. one with zero parameters, one with one, one with two, etc...

if so, how?

thanks!

What you want shall be called "polymorphic function-constructor". look on highdots.com/forums/javascript/… — Haim Evgi
– Haim Evgi, Commented Feb 7, 2011 at 9:32
Possible duplicate of JavaScript pattern for multiple constructors — Suma
– Suma, Commented Feb 24, 2017 at 9:31

deceze · Accepted Answer · 2011-02-07 09:40:03Z

9

No, Javascript does not support function overloading.

However, inside every function you have access to an arguments object, which holds all the arguments supplied to the function, declared or not. You can simply look at it and decide what exactly you want to do in your constructor.

Bad, unrefined example:

function Foo() {

    function singleParamConstructor(foo) {
        ...
    }
    function twoParamConstructor(foo, bar) {
        ...
    }

    switch (arguments.length) {
        case 1 :
            singleParamConstructor(arguments[0]);
            break;
        case 2 :
            twoParamConstructor(arguments[0], arguments[1]);
            break;
        ...
    }
}

edited Feb 7, 2011 at 9:40

answered Feb 7, 2011 at 9:34

deceze♦

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2 Comments

FranXh Over a year ago

Is there any other way apart from this one?

deceze Over a year ago

Well, no, Javascript does not support function overloading. There are probably innumerable design patterns with which you can avoid getting into a situation in which you think you need function overloading to begin with though.

Community · Accepted Answer · 2017-05-23 10:29:49Z

1

this might help: JavaScript constructor parameter types

edited May 23, 2017 at 10:29

CommunityBot

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answered Feb 7, 2011 at 9:33

Davide Piras

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