parcel-bundler/src/builtins/css-loader.js

<p align="center"> <a href="https://parceljs.org/" target="_blank"> <img alt="Parcel" src="https://user-images.githubusercontent.com/19409/31321658-f6aed0f2-ac3d-11e7-8100-1587e676e0ec.png" width="749"> </a> </p>

var bundle = require('./bundle-url');

function updateLink(link) {
  var newLink = link.cloneNode();
  newLink.onload = function () {
    link.remove();
  };
  newLink.href = link.href.split('?')[0] + '?' + Date.now();
  link.parentNode.insertBefore(newLink, link.nextSibling);
}

var cssTimeout = null;
function reloadCSS() {
  if (cssTimeout) {
    return;
  }

  cssTimeout = setTimeout(function () {
    var links = document.querySelectorAll('link[rel="stylesheet"]');
    for (var i = 0; i < links.length; i++) {
      if (bundle.getBaseURL(links[i].href) === bundle.getBundleURL()) {
        updateLink(links[i]);
      }
    }

    cssTimeout = null;
  }, 50);
}

module.exports = reloadCSS;