[removed] Extend a Function

Question

The main reason why I want it is that I want to extend my initialize function.

Something like this:

// main.js

window.onload = init();
function init         


        

Answer 1

This is very simple and straight forward. Look at the code. Try to grasp the basic concept behind javascript extension.

First let us extend javascript function.

function Base(props) {
    const _props = props
    this.getProps = () => _props

    // We can make method private by not binding it to this object. 
    // Hence it is not exposed when we return this.
    const privateMethod = () => "do internal stuff" 

    return this
}

You can extend this function by creating child function in following way

function Child(props) {
    const parent = Base(props)
    this.getMessage = () => `Message is ${parent.getProps()}`;

    // You can remove the line below to extend as in private inheritance, 
    // not exposing parent function properties and method.
    this.prototype = parent
    return this
}

Now you can use Child function as follows,

let childObject = Child("Secret Message")
console.log(childObject.getMessage())     // logs "Message is Secret Message"
console.log(childObject.getProps())       // logs "Secret Message"

We can also create Javascript Function by extending Javascript classes, like this.

class BaseClass {
    constructor(props) {
        this.props = props
        // You can remove the line below to make getProps method private. 
        // As it will not be binded to this, but let it be
        this.getProps = this.getProps.bind(this)
    }

    getProps() {
        return this.props
    }
}

Let us extend this class with Child function like this,

function Child(props) {
    let parent = new BaseClass(props)
    const getMessage = () => `Message is ${parent.getProps()}`;
    return { ...parent, getMessage} // I have used spread operator. 
}

Again you can use Child function as follows to get similar result,

let childObject = Child("Secret Message")
console.log(childObject.getMessage())     // logs "Message is Secret Message"
console.log(childObject.getProps())       // logs "Secret Message"

Javascript is very easy language. We can do almost anything. Happy JavaScripting... Hope I was able to give you an idea to use in your case.