this

问题 Some Scala APIs alias this to self , for example, trait Function1[-T1, +R] extends AnyRef { self => I know how this aliasing works in general, but don't see how traits such as Function1 benefit from it. Function1 does not use self anywhere in its definition except for the initial mention, so what is its purpose here? Variants of this question have been asked previously, but the answers are not directly applicable. Answers have discussed self types and inner classes, but I don't see how that

问题 When I write jQuery code, I use $(this) to change element: $('.classname').click(function(){ $(this).toggleClass('collapsed'); // .. }); Now I have are javascript class, looks like this: class CabinetFormSize { constructor() { this.cabinetBTN = $(".cabinetBTN"); this.events(); } events() { this.cabinetBTN.click(this.toggleMenu.bind(this)); } toggleMenu() { console.log($(this)); this.cabinetBTN.toggleClass('d-none'); } } If i write this in toggleMenu() I have class instance, but I need the

问题 I am having an issue in one of my components in Angular2 where as 'this' is bound to wrong context within one of my components. I have other components where this issue is not occurring but I cannot see what the difference is. Here is my code: Component: import { Component, Input } from '@angular/core'; import { FilesService } from "./services/files.service"; @Component({ selector: 'my-app', moduleId: module.id, templateUrl:'/app/views/app.html' }) export class AppComponent { openFileUploader

问题 I am creating a model in typescript in mongoose and I would like to use a required function, however unlike normal javascript, I cannot use the 'this' operator as typescript doesn't recognize the scope. I would like to access the value of another one of the objects properties, but I am not sure how to do it. Here is what I am looking for: export interface IUser extends mongoose.Document { name: string; somethingElse?: number; }; export const UserSchema = new mongoose.Schema({ name: {type

问题 I'm reusing an old application (a game) so it's possible to run several games at ones. By that reason I've changed the properties to "this.propery", which are used everywhere in my application. However, the only prototype function that can access the properties is "startGame". I have tried both "this.bricks" and "Game.bricks", but both are undefined when trying to reach them in any other function that "startGame". Any tips for me? var game = new Game(); game.startGame(); Game = function(){

问题 I am confused: why with inline onlick, we have to write onclick="hello()", but in JS, we should write btn.onclick=hello or btn.addEventListener('click',hello); for regular function, why with inline onlick, "this" refers to window, but with js call, "this" refers to button. I don't understand last two buttons according to w3school, In a function, this refers to the global object. https://www.w3schools.com/js/js_this.asp In regular functions the this keyword represented the object that called

问题 I am confused: why with inline onlick, we have to write onclick="hello()", but in JS, we should write btn.onclick=hello or btn.addEventListener('click',hello); for regular function, why with inline onlick, "this" refers to window, but with js call, "this" refers to button. I don't understand last two buttons according to w3school, In a function, this refers to the global object. https://www.w3schools.com/js/js_this.asp In regular functions the this keyword represented the object that called

问题 I have read this paragraph about the this keyword : https://bonsaiden.github.io/JavaScript-Garden/#function.this In this first case this refers to global objet, and it seems totally normal because when we have an arrow function, it automatically bind this with the one in the outer scope. var obj = { foo : () => console.log(this) } console.log(obj); obj.foo() However, I'm not able to explain the following behavior : function bar(){ this.foo = () => console.log(this) } var obj = new bar()

问题 class C{ //methods and properties } void C::some_method(C* b){ delete this; this = b; } This gives me follwing error when compiling: error: lvalue required as left operand of assignment My intention: Say there are objects a and b of class C. The contents of the class C can be very huge and field by field copying can be very costly. I want all the contents of ' a ' to be replaced by ' b ' in an economical way. Will default copy constructor do the intended task? I found something called 'move

问题 If i want to destruct an Object i would do : const obj = { a: 'a', fn: () => 'some function' } // const fn = obj.fn; // OR const { a, fn } = obj; console.log( fn() ); this doesn't work for the Date Object : Uncaught TypeError: this is not a Date object. const date = new Date(); const day = date.getDate(); console.log(day); // works const { getDate } = date; console.log( getDate() ); // doesn't work Why is this possible with the first Object and not with the Date ? how would one acheive that