How to reference a global variable referenced already in parameter on a function?

Question

Let say globalX is a global object variable. Lets define a function that takes that variable and inside another function takes same variable and changes the value inside it.

var globalX = [];

function a1(globalX){

a2(globalX);
console.log(globalX);
 //it shows "[]" not "[5,10]";

}

function a2(globalX){
globalX = [5,10];
}   

a1(globalX);

When I consoled that variable, console shows only parameter value in a1 not changed value in a2 function. How to reference changed value after calling a2?

Answer 1

In browser environments, you can refer to global variables by explicitly referencing the window object:

var reallyGlobalX = window.globalX

In node.js, there is no window object, but global is available:

var reallyGlobalX = global.globalX

Note that the variable must really be global - if it is just another variable from the outer scope, you cannot reach it once the variable has been shadowed.