copy constructor in prototype.js

Question

In prototype.js you can create classes e.g. like this:

var MyClass = Class.create(
{
    initialize: function (par1, par2)
    {
        this.data = $R(par1, par2).toArray();
    }
});

and instantiate them through

var myObj = new MyClass(1, 7000);

Now, how can I copy this object? The following does not work:

var myObj2 = MyObj.clone();

In my specific case, I only need a shallow copy, i.e. the attributes of the instance can reference the same objects. Some way of defining a copy constructor would certainly be the most versatile option.

Is that possible? (Preferably without relying on prototype.js internals)

@Bergi: I don’t think this is a duplicate. Notice that I inquire about the class system of the prototype.js framework, not general javascript objects. — bodo, Mar 20 '16 at 12:14
@canaaerus: If I understood you correctly, you wanted to do it without prototype.js, so it's just a standard js object to copy? — Bergi, Mar 20 '16 at 12:16
@RajaprabhuAravindasamy: Thank you – that seems to work. (Even though Object.create is not specific to prototype.js) Maybe you could add this as an answer together with a short explanation. — bodo, Mar 20 '16 at 12:17
@Bergi: I meant without internals / implementation details, i.e. just using the prototype.js API. But a simplistic solution like Raj’s is close enough. — bodo, Mar 20 '16 at 12:18

Bergi · Accepted Answer · 2016-03-20T15:25:01.323

2

You can use Prototype's Object.extend (or the native ES6 Object.assign) to copy your properties onto a new instance of your class:

var MyClass = Class.create({
    initialize: function (par1, par2) {
        this.data = $R(par1, par2).toArray();
    },
    clone: function() {
        return Object.extend(Object.create(Object.getPrototypeOf(this)), this);
    }
});

edited Mar 20 '16 at 15:25

answered Mar 20 '16 at 12:24

Bergi

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copy constructor in prototype.js

1 Answers1