Apply function once

once.js

function once(fn, context) {
  var result;

  return function() {
    if(fn) {
      result = fn.apply(context || this, arguments);
      fn = null;
    }
    
    return result;
  }
}

// Usage
var canOnlyFireOnce = once(function() {
	console.log('Fired!');
});

canOnlyFireOnce(); // "Fired!"
canOnlyFireOnce(); // nada

/*
  Many JavaScript toolkits offer this as a feature but the code 
  to accomplish this feat is so small that it's good to have
  available in the case that you can dodge a JavaScript toolkit!
  - David Walsh, https://davidwalsh.name/javascript-once
*/