jsdom/lib/jsdom/living/nodes/GlobalEventHandlers-impl.js

A JavaScript implementation of many web standards

"use strict";

const { appendHandler, createEventAccessor } = require("../helpers/create-event-accessor");
const isWindow = require("../helpers/is-window");
const { globalEventHandlersEvents, windowEventHandlersEvents } = require("../../../generated/event-sets");
const { mixin } = require("../../utils");

// These events are specified on GlobalEventHandlers but, per the HTML spec, are reflected on the Window from the body
// element. They are not derivable from the IDL alone.
const windowReflectingBodyElementEvents = new Set(["blur", "error", "focus", "load", "resize", "scroll"]);

class GlobalEventHandlerHelpers {
  _initGlobalEvents() {
    this._eventHandlers = null;
  }

  _getEventHandlerTarget(event) {
    // https://html.spec.whatwg.org/multipage/webappapis.html#determining-the-target-of-an-event-handler

    // Step 1
    if (this._localName !== "body" && this._localName !== "frameset") {
      return this;
    }

    // Step 2
    if (!windowEventHandlersEvents.has(event) && !windowReflectingBodyElementEvents.has(event)) {
      return this;
    }

    // Step 3 + 4
    const window = this._ownerDocument._defaultView;
    return window || null;
  }

  _getEventHandlerFor(event) {
    const target = this._getEventHandlerTarget(event);
    if (!target) {
      return null;
    }

    if (target._eventHandlers === null) {
      return null;
    }

    return target._eventHandlers[event];
  }

  _setEventHandlerFor(event, handler) {
    const target = this._getEventHandlerTarget(event);
    if (!target) {
      return;
    }

    const isRegistered = target._eventHandlers !== null && event in target._eventHandlers;
    if (!isRegistered) {
      if (handler === null) {
        return;
      }

      if (target._eventHandlers === null) {
        target._eventHandlers = Object.create(null);
      }

      appendHandler(target, event);
    }
    target._eventHandlers[event] = handler;
  }

  _globalEventChanged(event) {
    const propName = "on" + event;
    if (!(propName in this)) {
      return;
    }

    // Only translate attribute changes into properties when runScripts: "dangerously" is set.
    // Documents without a browsing context (i.e. without a _defaultView) never run scripts.
    const window = isWindow(this) ? this : this._ownerDocument._defaultView;
    if (!window || window._settings.runScripts !== "dangerously") {
      return;
    }

    const val = this.getAttributeNS(null, propName);
    const handler = val === null ? null : { body: val };
    this._setEventHandlerFor(event, handler);
  }
}

function installGlobalEventHandlerHelpers(target) {
  mixin(target, GlobalEventHandlerHelpers.prototype);
}

class GlobalEventHandlersImpl {}

installGlobalEventHandlerHelpers(GlobalEventHandlersImpl.prototype);

for (const event of globalEventHandlersEvents) {
  createEventAccessor(GlobalEventHandlersImpl.prototype, event);
}

module.exports = {
  implementation: GlobalEventHandlersImpl,
  installGlobalEventHandlerHelpers
};