CODEWITHSUNDEEP
javascriptfunction
George Smith
George Smith

Reputation: 505

How to call a function from outside the main function?

I am currently trying to learn javascript and what I want to achieve is to call a function, from outside the main function. For a better idea, I left the code which I am currently exercising on. I will be extremely grateful If someone can explain to me why exactly this function is not working. Thank you in advance. 

function One_Main(){
    function Alpha(){
        console.log("Alpha");
    }
}
One_Main(); 



function Two_Main(){
    Alpha();
}
Two_Main();

Upvotes: 0

Views: 271

Answers (4)

smac89
smac89

Reputation: 43147

It's not working because Alpha is not visible outside of One_Main.

To make it visible, you can define One_Main as an object, then make Alpha a property of One_Main.

To fix your code, do this:

function One_Main() {
  this.Alpha = function() {
    console.log("Alpha");
  }
}

// Make it visible
Alpha = new One_Main().Alpha;

function Two_Main() {
  Alpha();
}
Two_Main();

ES2015 Style

class One_Main {
    constructor() {}
    static Alpha() {
        console.log("Alpha");
    }
}

// Make it visible
Alpha = One_Main.Alpha;

function Two_Main() {
    Alpha();
}

Two_Main();

As a simple property in pure JS

function One_Main() {}

One_Main.Alpha = function() {
  console.log("Alpha");
}

// Make it visible
Alpha = One_Main.Alpha;

function Two_Main() {
  Alpha();
}

Two_Main();

Upvotes: 1

Pablo Cesar Cordova Morales
Pablo Cesar Cordova Morales

Reputation: 1138

I dont know what tutorial are you studying, maybe you are reading about currying method, if that is the case, you can make:

function One_Main(){
    function Alpha(){
        console.log("Alpha");
    }
    return Alpha;
}
One_Main(); 

function Two_Main(){
    One_Main()();
}
Two_Main();

Upvotes: 1

pmuntima
pmuntima

Reputation: 628

You might want to read about scoping in javascript to understand the problem. https://scotch.io/tutorials/understanding-scope-in-javascript

The function Alpha is not visible inside the Two_Main function

PS: Debugging is useful to learn more about the error. In Chrome you can right click and select Inspect element and look at the console to debug javascript.

Checkout https://raygun.com/blog/debug-javascript/ for more information

Upvotes: 1

Matt
Matt

Reputation: 718

Alpha() is in the scope of One_Main, you can't see it from the global scope. To call Alpha() from outside of One_Main you need to declare it outside of that function. 

function Alpha(){
    console.log("Alpha");
}

function One_Main(){
    Alpha();
}
One_Main(); 



function Two_Main(){
    Alpha();
}
Two_Main();

Upvotes: 2

Related Questions