AI solution for JavaScript Coding Question on BFE.dev
53. write your own `extends` in es5

Here's one possible solution using ES5 syntax:

function myExtends(SuperType, SubType) {  function F() {} // create a temporary constructor function  F.prototype = SuperType.prototype; // set the prototype of F to be the same as SuperType's prototype  SubType.prototype = new F(); // create a new prototype object for SubType that inherits from F's prototype  SubType.prototype.constructor = SubType; // reset the constructor property of SubType's prototype  return SubType; // return the new subtype constructor}

Explanation:

1. First, we create a new constructor function F that doesn't do anything, just for the purpose of temporarily storing a copy of SuperType's prototype.

2. We then set the prototype of F to be the same as SuperType's prototype, so that F now inherits from SuperType.

3. Next, we create a new prototype object for SubType by instantiating F. This means that SubType now inherits from F and therefore from SuperType.

4. Finally, we reset the constructor property of SubType's prototype to point back to SubType.

5. We return SubType, which now has a prototype chain that includes both F and SuperType.

With this new myExtends function, we can create subtypes that inherit from super types:

const InheritedSubType = myExtends(SuperType, SubType);console.log(new InheritedSubType('example')); // SubType { name: 'example', forSub: [ 3, 4 ], from: 'sub' }console.log(InheritedSubType.staticSuper); // staticSuperconsole.log(InheritedSubType.staticSub); // staticSubconsole.log(typeof InheritedSubType.superMethod); // functionconsole.log(typeof InheritedSubType.subMethod); // function

The InheritedSubType constructor now inherits both from SuperType and SubType and has access to all their properties and methods.