Listens for changes in a stylesheet

onStyleChange.js

// listen for changes in a stylesheet every 100ms (can change to fit needs)
function onStyleChange (stylesheet, callback) {
  // gets the entire CSSText of a stylesheet
  var getCSSText = function (stylesheet) {
        stylesheet = stylesheet.sheet.cssRules;

        var i, rules = '';

        for (i in stylesheet) {
          rules += stylesheet[i].cssText || '';
        }

        return rules;
      },

      origin = getCSSText(stylesheet), // source stylesheet
      clone = origin; // clone for comparison

  // listener
  setInterval(function () {
    origin = getCSSText(stylesheet);

    if (clone != origin) {
      callback();
      clone = origin; // update clone with new CSS
    }
  }, 100);
};

/*

// EXAMPLE USAGE
onStyleChange(document.querySelector('link[rel="stylesheet"]'), function () {
  console.log('CSS Changed');
});

*/