Question

if i have:

function Base (){
    this.sayHi = function(){
        alert('hi');
    }
}

function Thing (val){
    this.value = val;
}

var bob = new Thing("bob");

Is there some way I can now say that bob inherits from Base so that I could call:

bob.sayHi();

Basically have all the methods and properties of the Base class available on that instance?

A more relevant example with solution based on CMS’s post:

Here Items could represent data returned by the server..

var Items = [
    { sku: 123, type:'buggy', title:'This is a title', description: 'this is a description' },
    { sku: 234, type: 'baby-monitor', title: 'This is a title 2', description: 'this is a description 2' }
]

function ItemMethods() {
    this.BannerHTML = function () {
        return '<div class="banner _item_' + this.type + '_' + this.sku + '"><h2>' +
            this.title + '</h2><p>' +
            this.description + '</p></div>';
    };
}

Items.GetBySKU = function (code) {
    for (var i = 0; i < Items.length; i++) {
        if (Items[i].sku == code) {
            return Items[i];
        }
    }
};

$.each(Items, function (i, item) {
    ItemMethods.apply(item);
});

alert(Items.GetBySKU(234).BannerHTML());

Any further comments or solutions gladly accepted.. always interested in potential solutions to a problem 😉

Answer 1

Note that the properties that you create within the constructor, have nothing to do with the constructor’s prototype, they are own properties of the object you create using new Base();, they are not inherited. However, I think what you want to do it to apply the Base constructor function on the newly created object of Thing:

function Base (){
    this.sayHi = function(){
        alert('hi');
    }
}

function Thing (val){
    Base.apply(this, arguments);
    this.value = val;
}

var bob = new Thing("bob");
bob.sayHi();

Note that bob will not inherit from Base (it won’t have access to properties added to Base.prototype)

bob instanceof Base;  // false
bob instanceof Thing; // true