How do I change the value of a global variable inside of a function

Question

I am using JavaScript and I create a global variable. I define it outside of a function and I want to change the global variable value from inside a function and use it from

Answer 1

var a = 10;

myFunction(a);

function myFunction(a){
   window['a'] = 20; // or window.a
}

alert("Value of 'a' outside the function " + a); //outputs 20

With window['variableName'] or window.variableName you can modify the value of a global variable inside a function.