Changing an Object's Type in JavaScript

javascript javascript-objects
Ray picture Ray · Jul 2, 2010 · Viewed 13.9k times · Source

I have an array of existing object defined with JSON. The objects are obviously of the Object type. How do I associate them with a custom object type to give them specific functionality?

Answer

Jeremy picture Jeremy · Jul 2, 2010

The way that'll work in all browsers is to either augment each item in the array with the properties and methods you want, or pass the object to a constructor and create a new object based on the old object's properties and methods.

Or if you don't care about IE:

var obj = {
    name : "Jeremy"
};

function CustomType() {
    this.name = this.name || "someValue";
    this.greeting = "Hi";
}

CustomType.prototype.sayHi = function() {
    alert(this.greeting + ", " + this.name);
};

obj.__proto__ = CustomType.prototype;
obj.constructor.call(obj);

obj.sayHi();

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