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JavaScript JavaScript Basics (Retired) Creating Reusable Code with Functions Variable Scope

Mohammed Jammeh
Mohammed Jammeh
37,463 Points
Posted by Mohammed Jammeh
Mohammed Jammeh
37,463 Points

Accessing a variable inside a function..

Hi

I was wondering, how do you access a variable that is inside a function?

I have a function that generates a random number. The random number is then stored in a variable inside the function. However, when I try to access the random number value outside the function, it returns 'undefined' instead of the actual random number value.

How do I solve this?

Thanks..

4 Answers

David Tonge
PLUS
David Tonge
Courses Plus Student 45,640 Points
David Tonge
David Tonge
Courses Plus Student 45,640 Points

You must set function to "return" that variable. Then call the function instead. once you set that variable using the "var" keyword in the function it's gonna be local and you won't be able to access it unless its global (without var keyword) ... but that leads to hoisting problems and running the risk of overwriting that variable later.

Mohammed Jammeh
Mohammed Jammeh
37,463 Points
Mohammed Jammeh
Mohammed Jammeh
37,463 Points

Thanks for the reply.

I just want to be able to access the variable in the function, and not call the actual function. However, I am guessing that's impossible but I have tried making the variable global by removing the var keyword. On the other hand, as you have mentioned, this is risky. This is where I am stuck at, I'm thinking of either taking the risk or changing my overall approach just to be able to access the variable.

Chyno Deluxe
Chyno Deluxe
16,936 Points
Chyno Deluxe
Chyno Deluxe
16,936 Points

Another option would be to declare the variable outside of the function and overwrite the variable within the function.

var x = 0;

function myFunc(){
  x = 2;
}

console.log(x); // returns 0;

myFunc();

console.log(x); // returns 2
Mohammed Jammeh
Mohammed Jammeh
37,463 Points
Mohammed Jammeh
Mohammed Jammeh
37,463 Points

Thanks for the reply.

This is the option I am using at the moment but as David said, this is a risky method so I'm kind of contemplating whether to keep it or to try another option.

Chyno Deluxe
Chyno Deluxe
16,936 Points

Yes you want to limit the amount of global variables but if you use this method within another function then it wouldn't be a global variable but a private one.

(function(){
var x = 0;

function myFunc(){
  x = 2;
}

console.log(x); // returns 0;

myFunc();

console.log(x); // returns 2
}());

console.log(x) //returns x is not defined
Saleh '
Saleh '
24,986 Points
Saleh '
Saleh '
24,986 Points 
function generate_random_number_in_a_variable(){

    var randomNumber = Math.random();

    return randomNumber
}

function return_a_random_number(){
    return Math.random();
}

console.log(generate_random_number_in_a_variable());

console.log(return_a_random_number());


/* OUTPUT ==
 0.7452114758687594
 0.8748426673123808
*/
Mohammed Jammeh
Mohammed Jammeh
37,463 Points
Mohammed Jammeh
Mohammed Jammeh
37,463 Points

Thanks for the replies guys, appreciate it. I will stick with using the global variable and removing the var in front of the variable in my function so that I can access it outside that function.