prototypal-inheritance

问题 How can I check instanceof without the proto chain in javascript? var EventEmitter = require('events').EventEmitter; var Foo = function(){ }; Foo.prototype = EventEmitter.prototype; var Bar = function(){ }; Bar.prototype = EventEmitter.prototype; var f = new Foo(); var b = new Bar(); f instanceof Foo; //returns true b instanceof Bar; //returns true f instanceof Bar; //returns true b instanceof Foo; //returns true Essentially, I want those last two lines to return false. How do I do that? 回答1:

问题 I'm diving more into Prototypal Inheritance with JavaScript. When Object.Create() is in use to create objects, can someone show what is going on under the hood? Does Object.Create() depend on new and constructor functions behind the scenes? 回答1: When Object.create() is in use to create objects, can someone show what is going on under the hood? Low level details. Object.create is pretty much a primitive operation - similar to what happens when an {} object literal is evaluated. Just try to

问题 I am under the impression that ES6 classes are basically a syntactic sugar around the ES5 objects system. As I am trying to run React without a transpiler, I figured that I could use just use the old syntax for defining object "classes" that "inherit" from React.Component. var Board = function(props, state) { var instance = {}; instance.props = props; instance.context = state; return(instance); }; Board.prototype = Object.create(React.Component.prototype); Board.prototype.render = function()

问题 I am under the impression that ES6 classes are basically a syntactic sugar around the ES5 objects system. As I am trying to run React without a transpiler, I figured that I could use just use the old syntax for defining object "classes" that "inherit" from React.Component. var Board = function(props, state) { var instance = {}; instance.props = props; instance.context = state; return(instance); }; Board.prototype = Object.create(React.Component.prototype); Board.prototype.render = function()

问题 I have an existing prototype hierarchy and I want to modify it so that the hierarchy is kept intact but an additional prototype is added to then end of it. instanceof should return true for all prototypes. I.e.: say I have B->A and I want to make it B->A->Base. Now instanceof should return true for A, B, Base. I tried using B.prototype.prototype and Object.setPrototypeOf(), but no luck in either case. Sample with Object.setPrototypeOf(): class A { do() { console.log("do A"); } } class B

问题 I'm learning prototypal inheritance in Javascript, and for my understanding I'm trying to use it to send the process into infinite recursive chaining. My idea of prototypal inheritance is that an object (which is a function) holds prototype link. Any instance of that object points to it. So if I say instance.someproperty it looks into the prototype chain of the parent object. Assuming this, If I just point function prototype list to itself, it should go into infinite loop when object tries to

问题 In this snippet of Google Closure javascript code involving a constructor, why is goog.base(this); necessary? Doesn't Foo already inherit from Disposable with goog.inherits(foo, goog.Disposable); ? goog.provide('Foo'); /** * @constructor * @extends {goog.Disposable} */ Foo = function() { goog.base(this); } goog.inherits(foo, goog.Disposable); foo.prototype.doSomething = function(){ ... } foo.prototype.disposeInternal = function(){ ... } 回答1: goog.inherits(childConstructor, parentConstructor)

问题 I'm trying to determine what is the best practice for declaring helper functions used by a javascript "class". For example: Method #1: // closure issues? function helper(param) { return compute(param); } function HeavilyInstantiated() {} HeavilyInstantiated.prototype.computeHard = function(params) { var someResult = helper(params.prop1); return someResult; } Method #2: function HeavilyInstantiated() {} // still, only one instance for all objects instantiated? HeavilyInstantiated.prototype

问题 I have such structure of entities: Product 1 -> N ProductCustomField 1 1 | | M M' Release 1 -> N' ReleaseCustomField ProductCustomField is kind of "prototype" - a list of fields which Release may have. I'd like to select a single Release object with all ReleaseCustomFields whose ProductCustomField are in the Product of which the Release is. Example: MySoft has custom field "downloadURL" with default value "". MySoft has release 1.0. This release has no ReleaseCustomFields, but because it is a

问题 I have such structure of entities: Product 1 -> N ProductCustomField 1 1 | | M M' Release 1 -> N' ReleaseCustomField ProductCustomField is kind of "prototype" - a list of fields which Release may have. I'd like to select a single Release object with all ReleaseCustomFields whose ProductCustomField are in the Product of which the Release is. Example: MySoft has custom field "downloadURL" with default value "". MySoft has release 1.0. This release has no ReleaseCustomFields, but because it is a