Understanding Class Inheritance in javascript

Asked 2 months ago, Updated 2 months ago, 1 views

I'm a beginner at javascript
I would like to inherit the Array class of javascript and create a new class of my own class.Previously, I inherited ArrayList in Java and created it, so I wrote the following code with reference to automatic conversion in jsweet.I created a method unnest that eliminates any nesting in the list.

var SuperArray=(function(){
        if(((c!=null&&(c instance of Array))||c===null)){
            var__args = Array.prototype.slice.call(arguments);
        else if(c===undefined) {
            var__args = Array.prototype.slice.call(arguments);
            US>throw new Error ('invalid overload');
    SuperArray.prototype = Object.create (SuperArray.prototype, {value:{constructor:SuperArray}});
        varlist=(function(){var_o=new SuperArray();_o.__delegate=[];return_o;})());
            if(o!=null&o instance of SuperArray) {
                /* addAll*/(function(l1,l2) {return l1.push.apply(l1,l2);}) (list.__delegate,o.unnest());
                /* add*/(list.__delegate.push(o)>0);
        return list;
    return SuperArray;

Chrome generated the error Uncaught TypeError: Cannot read property 'length' of undefined when creating an object for the SuperArray class.Since SuperArray inherits Array, I thought I could use the length parameter...
By the way, you can list.length to SuperArray object list, but list.unnest().length will cause the above error.
I studied inheritance and protocol, but there are many things I don't understand.It seems that there are many things that I misunderstood, but it would be very helpful if you could tell me.Thank you for your cooperation.

Additional information below

8/14 15:50
_delegate and constructor are marked as jsweet.I don't really want to throw a whole ball, but there are many things I don't understand even if I look into it, so I would appreciate it if you could tell me about a website that I can refer to.


2022-09-30 11:41

1 Answers

SuperArray has not succeeded to Array

-SuperArray.prototype=Object.create(SuperArray.prototype, {value:{constructor:SuperArray}});
+ SuperArray.prototype = Object.create (Array.prototype, {value:{constructor:SuperArray}});

I think it's going to work in

When inheriting complex built-in objects such as Array and RegExp, it is preferable to inherit using the extends keyword rather than using the Object.create to inherit them.

class SuperArray extensions Array {}
var superArray1 = new SuperArray(1,2,3);
console.info (...superArray1); // 1, 2, 3
superArray1.length = 0;
console.info(...superArray1); // undefined

Array features that manipulate index properties when manipulating length properties are also inherited

If the environment is not available after ES6, I think it would be better to convert it to ES5 in Babel.
There is also an online repl, so why don't you try it?


2022-09-30 11:41

If you have any answers or tips

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