console.log在Angular2组件(Typescript)中不起作用 [英] console.log not working in Angular2 Component (Typescript)

问题描述

我对Angular2和Typescript都比较陌生.由于typescript是javascript的超集，因此我希望像console.log这样的功能可以正常工作. console.log在组件​​类外部时可以在.ts文件中完美运行，但不能像我期望的那样从组件类内部运行.

I am relatively new to both Angular2 and typescript. Since typescript is a superset of javascript, I'd expect functions like console.log to work. console.log works perfectly in .ts files when outside a component class but does not work as I'd expect from inside the component class.

// main.ts

import { Component } from '@angular/core';
console.log("Hello1"); //1. This works perfectly

@Component({..)
export class App {
 s: string = "Hello2";
 // console.log(s); //2. This gives compilation error (when uncommented)
 // Error: Function implementation is missing or not immediately following the declaration.
}

有什么我想念的吗?

推荐答案

它不起作用，因为console.log()不在类"App"的可执行区域"中.

It's not working because console.log() it's not in a "executable area" of the class "App".

类是由属性和方法组成的结构.

A class is a structure composed by attributes and methods.

执行代码的唯一方法是将其放在要执行的方法中.例如:constructor()

The only way to have your code executed is to place it inside a method that is going to be executed. For instance: constructor()

console.log('It works here')

@Component({..)
export class App {
 s: string = "Hello2";
            
  constructor() {
    console.log(this.s)            
  }            
}

像普通的javascript对象一样思考类.

Think of class like a plain javascript object.

期望它能奏效吗?

class:  {
  s: string,
  console.log(s)
 }

如果仍然不确定，请尝试打字机游乐场，在这里您可以看到您的打字机代码已生成为纯JavaScript.

If you still unsure, try the typescript playground where you can see your typescript code generated into plain javascript.

https://www.typescriptlang.org/play/index.html

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