es6-class

问题 In React quickstart, it is stated about Refs and Functional Components that You may not use the ref attribute on functional components because they don't have instances: function MyFunctionalComponent() { return <input />; } class Parent extends React.Component { render() { // This will *not* work! return ( <MyFunctionalComponent ref={(input) => { this.textInput = input; }} /> ); } } I don't fully understand the above statement and the example. So far from reading the tutorials, the only

来源： https://stackoverflow.com/questions/47517149/unexpected-token-for-class-properties-in-node-8-4

来源： https://stackoverflow.com/questions/47517149/unexpected-token-for-class-properties-in-node-8-4

来源： https://stackoverflow.com/questions/47517149/unexpected-token-for-class-properties-in-node-8-4

来源： https://stackoverflow.com/questions/52242521/typeerror-this2-setstate-is-not-a-function-cant-bind-state

问题 Using ES6 class syntax, is it possible to create a new instance of the current class from the parent? For example: class Base { withFoo() { return new self({ foo: true }); } } class Child extends Base {} (new Child()).withFoo(); I'm looking for something similar to PHP's new self() syntax. 回答1: You can access the current instance's constructor via this.constructor . 来源： https://stackoverflow.com/questions/42161828/es6-classes-is-it-possible-to-access-the-constructor-of-a-child-class-from-the

问题 I'm trying to use a static variable in es6. I'd like to declare a static variable count in Animal class and increase it. However, I couldn't declare a static variable through static count = 0; , so I tried another way like this: class Animal { constructor() { this.count = 0; } static increaseCount() { this.count += 1; } static getCount() { return this.count; } } console.log(Animal.increaseCount()); // undefined console.log(Animal.getCount()); // NaN I expected console.log(Animal.getCount());

问题 So when they created es6 classes they just made everything public by default, and that was a bit odd to me but I just went with it, given I still used the older es5 style scope based classes. Anyway a few years on now we are getting private members in classes, which seems great, but then you look at the synax: somePublicVar = 10; #somePrivateVar = 20; As you can see we now have to prefix the private stuff with the hash/pound sign which seems a very odd choice given JS has public and private

问题 In Javascript, with the following illustration code: class Base { constructor() { this._val = 1 } get val() { return this._val } } class Xtnd extends Base { set val(v) { this._val = v } } let x = new Xtnd(); x.val = 5; console.log(x.val); // prints 'undefined' the instance x will not inherit get val()... from Base class. As it is, Javascript treat the absence of a getter, in the presence of the setter, as undefined. I have a situation in which I have many classes that all have the exact same

问题 In Javascript, with the following illustration code: class Base { constructor() { this._val = 1 } get val() { return this._val } } class Xtnd extends Base { set val(v) { this._val = v } } let x = new Xtnd(); x.val = 5; console.log(x.val); // prints 'undefined' the instance x will not inherit get val()... from Base class. As it is, Javascript treat the absence of a getter, in the presence of the setter, as undefined. I have a situation in which I have many classes that all have the exact same