javascript: different constructors for same type of object - Stack Overflow

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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!

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!

• javascript
• multiple-constructors

Share Improve this question Follow edited Feb 7, 2011 at 9:30 Haim Evgi 126k4646 gold badges222222 silver badges226226 bronze badges asked Feb 7, 2011 at 9:29 clampclamp 34k7575 gold badges207207 silver badges305305 bronze badges 2

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

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2 Answers 2

Sorted by: Reset to default 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;
        ...
    }
}

this might help: JavaScript constructor parameter types

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