console.log not working in Angular2 Component (Typescript)

Question

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.
}

Is there anything that I am missing?

Answer 1

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

A class is a structure composed by attributes and methods.

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)            
  }            
}

Think of class like a plain javascript object.

Would it make sense to expect this to work?

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

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

Answer 2

The console.log should be wrapped in a function , the "default" function for every class is its constructor so it should be declared there.

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

 @Component({
  selector: 'hello-console',
})
    export class App {
     s: string = "Hello2";
    constructor(){
     console.log(s); 
    }

}