使用下划线继承 [英] inheritance using underscore

问题描述

我已经上过课 -

Zoo.Controller = (function() {

  function Controller() {}

  Controller.prototype.params = {};

  Controller.prototype.set_params = function(params) {
    this.params = params;
    return this;
  };

  return Controller;

})();

我希望使用_.extend继承该类

and I want to inherit from that class using _.extend

Zoo.Controllers.WhaleController = _.extend({

  new: function () {
    // do something
  }

}, Zoo.Controller);

当我尝试像这样实例化那个类时......

When I try to instantiate that class like so...

this.whale_controller = new Zoo.Controllers.WhaleController();

我得到 -

Uncaught TypeError: object is not a function

是否有可能做我做的事情我在尝试？我在JS中读过很多关于继承的文章，但是假设Underscore库已经为我解决了。

Is it possible to do what I'm trying? I've read multiple articles on inheritance in JS, but had assumed that the Underscore library had it solved for me.

推荐答案

正如Bergi指出的那样;在JavaScript中继承并不难。您应该知道构造函数的作用以及使用的原型。 这个答案可能对此有所帮助，我试图通过简单且希望易于理解的示例来演示原型。您可以在浏览器JS命令行中复制并粘贴代码（在控制台中）并更改它以查看您是否了解原型在JavaScript中的行为。

As Bergi pointed out; it isn't hard to inherit in JavaScript. You should know what a constructor function does and what prototype is used for. This answer may help with that, I tried to demonstrate prototype through simple and hopefully easy to understand examples. You can copy and paste the code in your browsers JS commandline (in the console) and change it to see if you understand how prototype behaves in JavaScript.

从ZooController继承你可以：

To inherit from ZooController you can:

Zoo.Controllers.WhaleController = function(args){
  Zoo.Controller.apply(this,arguments);//re use Zoo.Controller constructor
                                  //and initialize instance variables
  //instance specific members of Whale using an args object
  this.weitht=args.weight||4;
  this.wu=args.weightUnit||wu.metricTon;
  //Zoo.Controller.call(this,arg1,arg2); can be used too but I usually use
  // an args object so every function can pick out and mutate whatever they want
  // for example: var w = new WhaleController({weight:3,weightUnit:wu.metricTon});
  // now it looks more like pythons optional arguments: fn(spacing=15, object=o)
};
//set Zoo.controller.prototype to a shallow copy of WhaleController.prototype
//may have to polyfill the Object.create method if you want to support older browsers
Zoo.Controllers.WhaleController.prototype=Object.create(Zoo.Controller.prototype);
//repair constructor
Zoo.Controllers.WhaleController.prototype.constructor=Zoo.Controllers.WhaleController;
//extend Zoo.controller.prototype.set_params
Zoo.Controllers.WhaleController.prototype.set_params=function(){
  //re use parent set_params
  Zoo.Controller.prototype.set_params.apply(this,arguments);
  //and do something extra
  console.log("extra in set_params from WhaleController");
};
//WhaleController own function
Zoo.Controllers.WhaleController.prototype.whaleSpecific=function(){
  //funciton specific to WhaleController
};

Object.create的Polyfill 这里。

Polyfill for Object.create here.

这篇关于使用下划线继承的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！