hotModuleReplacement.js

/* eslint-env browser */
/*
  eslint-disable
  no-console,
  func-names
*/

const normalizeUrl = require('normalize-url');

const srcByModuleId = Object.create(null);

const noDocument = typeof document === 'undefined';

const { forEach } = Array.prototype;

function debounce(fn, time) {
  let timeout = 0;

  return function() {
    const self = this;
    // eslint-disable-next-line prefer-rest-params
    const args = arguments;

    const functionCall = function functionCall() {
      return fn.apply(self, args);
    };

    clearTimeout(timeout);
    timeout = setTimeout(functionCall, time);
  };
}

function noop() {}

function getCurrentScriptUrl(moduleId) {
  let src = srcByModuleId[moduleId];

  if (!src) {
    if (document.currentScript) {
      ({ src } = document.currentScript);
    } else {
      const scripts = document.getElementsByTagName('script');
      const lastScriptTag = scripts[scripts.length - 1];

      if (lastScriptTag) {
        ({ src } = lastScriptTag);
      }
    }

    srcByModuleId[moduleId] = src;
  }

  return function(fileMap) {
    if (!src) {
      return null;
    }

    const splitResult = src.split(/([^\\/]+)\.js$/);
    const filename = splitResult && splitResult[1];

    if (!filename) {
      return [src.replace('.js', '.css')];
    }

    if (!fileMap) {
      return [src.replace('.js', '.css')];
    }

    return fileMap.split(',').map((mapRule) => {
      const reg = new RegExp(`${filename}\\.js$`, 'g');

      return normalizeUrl(
        src.replace(reg, `${mapRule.replace(/{fileName}/g, filename)}.css`),
        { stripWWW: false }
      );
    });
  };
}

function updateCss(el, url) {
  if (!url) {
    // eslint-disable-next-line
    url = el.href.split('?')[0];
  }

  if (!isUrlRequest(url)) {
    return;
  }

  if (el.isLoaded === false) {
    // We seem to be about to replace a css link that hasn't loaded yet.
    // We're probably changing the same file more than once.
    return;
  }

  if (!url || !(url.indexOf('.css') > -1)) {
    return;
  }

  // eslint-disable-next-line no-param-reassign
  el.visited = true;

  const newEl = el.cloneNode();

  newEl.isLoaded = false;

  newEl.addEventListener('load', () => {
    newEl.isLoaded = true;
    el.parentNode.removeChild(el);
  });

  newEl.addEventListener('error', () => {
    newEl.isLoaded = true;
    el.parentNode.removeChild(el);
  });

  newEl.href = `${url}?${Date.now()}`;

  el.parentNode.appendChild(newEl);
}

function getReloadUrl(href, src) {
  let ret;

  // eslint-disable-next-line no-param-reassign
  href = normalizeUrl(href, { stripWWW: false });

  // eslint-disable-next-line array-callback-return
  src.some((url) => {
    if (href.indexOf(src) > -1) {
      ret = url;
    }
  });

  return ret;
}

function reloadStyle(src) {
  const elements = document.querySelectorAll('link');
  let loaded = false;

  forEach.call(elements, (el) => {
    const url = getReloadUrl(el.href, src);

    if (!isUrlRequest(url)) {
      return;
    }

    if (el.visited === true) {
      return;
    }

    if (url) {
      updateCss(el, url);
      loaded = true;
    }
  });

  return loaded;
}

function reloadAll() {
  const elements = document.querySelectorAll('link');

  forEach.call(elements, (el) => {
    if (el.visited === true) {
      return;
    }

    updateCss(el);
  });
}

function isUrlRequest(url) {
  // An URL is not an request if

  // 1. It's an absolute url
  if (/^[a-z][a-z0-9+.-]*:/i.test(url)) {
    return false;
  }

  // 2. It's a protocol-relative
  if (/^\/\//.test(url)) {
    return false;
  }

  // 3. Its a `#` link
  if (/^#/.test(url)) {
    return false;
  }

  return true;
}

module.exports = function(moduleId, options) {
  if (noDocument) {
    console.log('no window.document found, will not HMR CSS');

    return noop;
  }

  const getScriptSrc = getCurrentScriptUrl(moduleId);

  function update() {
    const src = getScriptSrc(options.filename);
    const reloaded = reloadStyle(src);

    if (options.locals) {
      console.log('[HMR] Detected local css modules. Reload all css');

      reloadAll();

      return;
    }

    if (reloaded && !options.reloadAll) {
      console.log('[HMR] css reload %s', src.join(' '));
    } else {
      console.log('[HMR] Reload all css');

      reloadAll();
    }
  }

  return debounce(update, 50);
};