Function override in JavaScript

Question

How to do function override in JavaScript ?

I have below code.

function helloWorld () {
    return 'helloworld ';
}

var origHelloWorld = window.helloWorld;

window.helloWorld = function() {
    return 'helloworld2';
}

alert(helloWorld);

I would like to get output like

helloworld helloworld2

What should I do ?

May be I described less. Actually I would like to call function the helloworld and I would like to get output of both functions jointly.

Call the original from your override and append the result to the return value. — DarthJDG, Sep 26 '17 at 08:49
You must read about prototypes in javascript, it'll probably help you. — sjahan, Sep 26 '17 at 08:51

score 1 · Answer 1 · answered Sep 26 '17 at 08:53

1

Try this:

function helloWorld () {
    return 'helloworld ';
}

var origHelloWorld = window.helloWorld;

window.helloWorld = function() {
    return origHelloWorld() + ' ' +'helloworld2';
}

alert( helloWorld() );

answered Sep 26 '17 at 08:53

colxi

7,640
2
45
43

Thanks @colxi for your reply. Your reply is correct if I only would like to print 'helloworld helloworld2'. But this is an example. I would like to get output of both function jointly whatever code is exists inside the functions. Thanks – abu abu Sep 26 '17 at 09:03
i don't understand, what do you mean? – colxi Sep 26 '17 at 12:02

score 0 · Answer 2 · answered Sep 26 '17 at 08:57

0

Are you sure, you understand override?

yours sample with the same parma, how to override it?

and javascript has not a method about the override, but you can override in other ways. you can follow other questions in stackoverflow

answered Sep 26 '17 at 08:57

Carson

152
11

score 0 · Answer 3 · answered Sep 26 '17 at 09:01

Using closures to avoid polluting the global namespace:

function helloWorld () {
    return 'helloworld ';
}

helloWorld = (function() {
    var original = window.helloWorld;
    return function () {
    return original() + ' helloworld2';
}})();

alert(helloWorld());

Function override in JavaScript

3 Answers3