How to create a global variable inside a function

Question

How do I set a global variable inside of a function? In the Treehouse video said it is bad practice to just drop the 'var' and put 'something = somethingelse', but it didn't offer an alternative.

Background: When the page loads the user is logged in with JS, so in order to access the current user I need to wait for that to happen. Once that has happened I would like to define some variables which would have data from the user. I have created a setInterval function to fire once the user is indentified, but I would like to use the variables defined inside the function outside of that function also.

Answer 1 · 2014-10-06T00:58:56Z

October 6, 2014 12:58am

If I'm understanding you correctly, there's a couple different ways you could do this.

For one, you can declare the variable(s) in the global space (preferably in a closure) but not assign it a value until you've retrieved that information from the user.

Example:

(function(){

var infoINeed;

function thingToDo() {
  infoINeed = "whatever";
}

thingToDo();

// then you can use it down here, too

function anotherThing(infoINeed) {
 // do something with infoINeed value...
}

})();

Another thing you could do would be to return an object upon getting the user information then pulling the content out of that object as needed.

function thingToDo() {
  var infoINeed = "whatever";
  return {
    thing1: infoINeed,
    thing2: "something else"
  };
}

// assign the executed function to a variable for easy use

var obj = thingToDo();


// Then, later, you can get that information, this way:

obj.thing1;

Does that make sense?

Answer 2 · 2014-10-06T01:17:11Z

October 6, 2014 1:17am

I had a mistake in the second version. I corrected it above.

Answer 3 · 2014-10-06T15:00:23Z

October 6, 2014 3:00pm

You could pass the "global" object into your IIFE (immediately invoked function expression).

;(function(window) {
  var myFunc = function() {
    console.log('in my func...');
    window.myVar = 5;
  };

  console.log(window.myVar); // -> undefined
  myFunc();

})(window);

console.log(myVar); // -> 5

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Marty Hitchcock

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How to create a global variable inside a function

3 Answers

Scott Vrable

Scott Vrable

Marty Hitchcock

Marty Hitchcock

Scott Vrable

Scott Vrable

Hunter Cassidy

Hunter Cassidy