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I have the following code:

this.myObject = {
   key1: "val1",
   key2: "val2"
}

this.aMethod = function (newObject) {
    ...

Here I want a new object (probably that inherits from this.myObject) that contains everything in this.myObject plus whatever is in newObject also, fields in newObject should override already existing fields in this.myObject

How do I do this?

This idea is that this.myObject provides some default values - but the user of the method can override these values. I'm open to criticisms of this overall "pattern" as well. Thanks.

I have the following code:

this.myObject = {
   key1: "val1",
   key2: "val2"
}

this.aMethod = function (newObject) {
    ...

Here I want a new object (probably that inherits from this.myObject) that contains everything in this.myObject plus whatever is in newObject also, fields in newObject should override already existing fields in this.myObject

How do I do this?

This idea is that this.myObject provides some default values - but the user of the method can override these values. I'm open to criticisms of this overall "pattern" as well. Thanks.

• javascript

Share Improve this question Follow edited Nov 11, 2010 at 13:19 Andrew Barber 40.2k2020 gold badges9797 silver badges124124 bronze badges asked Nov 11, 2010 at 13:10 bbabba 15.2k1111 gold badges3131 silver badges2626 bronze badges 11

• In the future, instead of asking your question in "code ments", ask it in the question text - people can see the question as containing text only and close it as "not a real question". – Oded Commented Nov 11, 2010 at 13:14
• Is this global code or function code? – Šime Vidas Commented Nov 11, 2010 at 13:22
• the code I showed above is itself inside of a prototype method – bba Commented Nov 11, 2010 at 13:31
• @bba I would like to see the whole pattern (the whole prototype method) – Šime Vidas Commented Nov 11, 2010 at 13:38
• That is pretty much the entire code. Just wrap it in something like: SomeObject.prototype.Method = function() { ... }; – bba Commented Nov 11, 2010 at 13:40

 |  Show 6 more ments

4 Answers 4

Sorted by: Reset to default 5

SomeObject.prototype.someMethod = function() {

    this.myObject = { key1: 1, key2: 2 };

    this.aMethod = function (o) {
        var newObject = object(this.myObject);

        for (var prop in o) {
            if (o.hasOwnProperty(prop)) {
                newObject[prop] = o[prop];
            }
        }

        // Now newObject contains all properties from the passed in object
        // and also inherits all properties from myObject

    };

};

Note: I am using the object function from @Marco's answer.

Thus spoke Douglas Crockford:

function object (o) {
  function F() {}
  F.prototype = o;
  return new F();
}

There are literally dozens of ways to do that. The videos at Yahoo Theater, and the books Javascript: The Good Parts and Object Oriented Javascript explore some trade-offs. Many javascript libraries implement a simple "class-like" inheritance pattern, but it's just a small piece of the whole cake.

this should do the work:

this.aMethod = function(newObject){
  binedObject = {};
  for(key in this.myObject){
    binedObject[key] = this.myObject[key];
  }
  for(key in newObject){
    binedObject[key] = newObject[key];
  }
  return binedObject;
}

or, if you are using jquery, in one line:

return $.extend({},this.myObject,newObject);

If this is what you're looking for:

var Base = function() {
    this.foo = "bar";
};

var MyClass = new Class({ extends: Base }, function() {

    this.myMethod = function() {
        return this.foo; // bar
    }

});

Check this out: Minified 2kb minimalistic library which you can use, https://github./haroldiedema/joii/

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