parcel-bundler/src/builtins/hmr-runtime.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 global = (1, eval)('this');
var OldModule = module.bundle.Module;
function Module() {
  OldModule.call(this);
  this.hot = {
    accept: function (fn) {
      this._acceptCallback = fn || function () {};
    },
    dispose: function (fn) {
      this._disposeCallback = fn;
    }
  };
}

module.bundle.Module = Module;

if (!module.bundle.parent && typeof WebSocket !== 'undefined') {
  var ws = new WebSocket('ws://localhost:{{HMR_PORT}}/');
  ws.onmessage = function(event) {
    var data = JSON.parse(event.data);

    if (data.type === 'update') {
      data.assets.forEach(function (asset) {
        hmrApply(global.require, asset);
      });

      data.assets.forEach(function (asset) {
        if (!asset.isNew) {
          hmrAccept(global.require, asset.id);
        }
      });
    }

    if (data.type === 'reload') {
      ws.close();
      ws.onclose = function () {
        window.location.reload();
      }
    }

    if (data.type === 'error-resolved') {
      console.log('[parcel] ✨ Error resolved');
    }

    if (data.type === 'error') {
      console.error('[parcel] 🚨  ' + data.error.message + '\n' + 'data.error.stack');
    }
  };
}

function getParents(bundle, id) {
  var modules = bundle.modules;
  if (!modules) {
    return [];
  }

  var parents = [];
  var k, d, dep;

  for (k in modules) {
    for (d in modules[k][1]) {
      dep = modules[k][1][d];
      if (dep === id || (Array.isArray(dep) && dep[dep.length - 1] === id)) {
        parents.push(+k);
      }
    }
  }

  if (bundle.parent) {
    parents = parents.concat(getParents(bundle.parent, id));
  }

  return parents;
}

function hmrApply(bundle, asset) {
  var modules = bundle.modules;
  if (!modules) {
    return;
  }

  if (modules[asset.id] || !bundle.parent) {
    var fn = new Function('require', 'module', 'exports', asset.generated.js);
    asset.isNew = !modules[asset.id];
    modules[asset.id] = [fn, asset.deps];
  } else if (bundle.parent) {
    hmrApply(bundle.parent, asset);
  }
}

function hmrAccept(bundle, id) {
  var modules = bundle.modules;
  if (!modules) {
    return;
  }

  if (!modules[id] && bundle.parent) {
    return hmrAccept(bundle.parent, id);
  }

  var cached = bundle.cache[id];
  if (cached && cached.hot._disposeCallback) {
    cached.hot._disposeCallback();
  }

  delete bundle.cache[id];
  bundle(id);

  cached = bundle.cache[id];
  if (cached && cached.hot && cached.hot._acceptCallback) {
    cached.hot._acceptCallback();
    return true;
  }

  return getParents(global.require, id).some(function (id) {
    return hmrAccept(global.require, id)
  });
}