Nodejs Set a global function and call a nested function-CodePudding

My Main function

import AppLauncher from './Applauncher'

function Mainfunc() {
 global.app=  AppLauncher()
 global.app.start('index')
}

AppLauncher.js

    function AppLauncher() {
      function start(opts){
              console.log('functions start called with'   opts)
        }
     }

   export default AppLauncher

I want to assign the AppLauncher function as global, and call the start function nested inside it

CodePudding user response：

Constructors are the way to go. You can do something like this:

// AppLauncher.js
function AppLauncher() {
  // run some code...
  // notice `this`
  this.start = function(opts) {
    console.log('start function called with', opts);
  }
}
export default AppLauncher;

In your main function, call it with the new keyword:

import AppLauncher from './AppLauncher';
function Mainfunc() {
  global.app = new AppLauncher();
  global.app.start('index');
}

Constructors can also be written as classes (you can use it the same way as in my last example):

class AppLauncher {
  constructor() {
    // Anything in here gets executed when once you create an object from this class with the `new` keyword
  }
  // Instead of `this` we add a method to the class:
  start(opts) {
    console.log('start function called with', opts);
  }
}

export default AppLauncher;

More about constructors: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Classes/constructor

If you don't want to use a constructor, you can also return an object:

// AppLauncher.js
function AppLauncher() {
  // Some code here...
  return {
    start(opts) {
      console.log("function start called with", opts);
    }
  };
}
export default AppLauncher;

And you can use this just like you thought:

import AppLauncher from `./AppLauncher`;
function Mainfunc() {
  global.app = AppLauncher();
  global.app.start('index');
}

As a side note, it's conventional to call constructors with PascalCase, while regular functions are called with camelCase.