Edit in JSFiddle

// Returns a function, that, as long as it continues to be invoked, will not
// be triggered. The function will be called after it stops being called for
// N milliseconds. If `immediate` is passed, trigger the function on the
// leading edge, instead of the trailing.
function debounce(func, wait, immediate) {
    var timeout;
    return function() {
        var context = this, args = arguments;
        var later = function() {
            timeout = null;
            if (!immediate) func.apply(context, args);
        var callNow = immediate && !timeout;
        timeout = setTimeout(later, wait);
        if (callNow) func.apply(context, args);

//  Test
var myEfficientFn = debounce(function() {
  // All the taxing stuff you do
  console.log("window resized");
}, 250);
window.addEventListener('resize', myEfficientFn);

  Resize the window and check the console to see the debounce() function running, but not triggering excessively.
body {
  font-family: arial;