jquery wait for element to exist

var checkExist = setInterval(function() {
   if ($('#the-canvas').length) {
      console.log("Exists!");
      clearInterval(checkExist);
   }
}, 100); // check every 100ms
//https://gist.github.com/chrisjhoughton/7890303

var waitForEl = function(selector, callback) {
  if (jQuery(selector).length) {
    callback();
  } else {
    setTimeout(function() {
      waitForEl(selector, callback);
    }, 100);
  }
};

waitForEl(selector, function() {
  // work the magic
});