Как я могу использовать async / await с mutationObserver / Arrive. js?

Question

Я использую библиотеку Arrive. js для прослушивания новых элементов, поступающих в DOM. Он использует Mutation Observers для наблюдения за созданием элементов DOM.

Я хотел бы использовать async / await в функции, чтобы заставить его ждать прибытия. js, чтобы выполнить свою задачу, прежде чем продолжить.

Вот мой код.

let run = async() => {
  
  console.log("begin run()");
  
  await setAndListen();
  
  console.log("end run() <-- this should be the last console.log()");
  
}


let setAndListen = async() => {

  console.log("beginning setAndListen()");
  
  document.arrive(".new", function() {
    
    console.log("new element arrived");
    
    // Using a setTimeout to *simulate* a delay.
    // In the real world, this code would naturally be delayed
    // because the element would take a few seconds to arrive 
    // in the DOM (an http request happens).
    // I'd like for the run() function should finish after 
    // this 2 second delay.
    setTimeout(function(){ 
      
      console.log("returning after 2 second delay");
      return
      
    }, 2000);


  });

  // Creating an element and adding it to the page.
  let newElement = document.createElement("div");
  newElement.classList.add("new");
  document.body.appendChild(newElement);
  
  console.log("end setAndListen()");

}

run();

<script src="https://cdnjs.cloudflare.com/ajax/libs/arrive/2.4.1/arrive.min.js"></script>

Вот ссылка на мой тестовый код на JS Bin. В начале она включает библиотеку Arrive. js, за которой следует приведенный выше код.

https://jsbin.com/nanisox/edit?js, консоль, вывод

Answer 1

Сделайте ваш setAndListen мгновенно вернуть Promise. Затем внутри обратного вызова setTimeout используйте resolve, чтобы выполнить обещание. Обещания отлично подходят для возврата значений внутри вложенных обратных вызовов.

Ознакомьтесь с приведенным ниже примером.

/*
 * arrive.js
 * v2.4.1
 * https://github.com/uzairfarooq/arrive
 * MIT licensed
 *
 * Copyright (c) 2014-2017 Uzair Farooq
 */

var Arrive=function(e,t,n){"use strict";function r(e,t,n){l.addMethod(t,n,e.unbindEvent),l.addMethod(t,n,e.unbindEventWithSelectorOrCallback),l.addMethod(t,n,e.unbindEventWithSelectorAndCallback)}function i(e){e.arrive=f.bindEvent,r(f,e,"unbindArrive"),e.leave=d.bindEvent,r(d,e,"unbindLeave")}if(e.MutationObserver&&"undefined"!=typeof HTMLElement){var o=0,l=function(){var t=HTMLElement.prototype.matches||HTMLElement.prototype.webkitMatchesSelector||HTMLElement.prototype.mozMatchesSelector||HTMLElement.prototype.msMatchesSelector;return{matchesSelector:function(e,n){return e instanceof HTMLElement&&t.call(e,n)},addMethod:function(e,t,r){var i=e[t];e[t]=function(){return r.length==arguments.length?r.apply(this,arguments):"function"==typeof i?i.apply(this,arguments):n}},callCallbacks:function(e,t){t&&t.options.onceOnly&&1==t.firedElems.length&&(e=[e[0]]);for(var n,r=0;n=e[r];r++)n&&n.callback&&n.callback.call(n.elem,n.elem);t&&t.options.onceOnly&&1==t.firedElems.length&&t.me.unbindEventWithSelectorAndCallback.call(t.target,t.selector,t.callback)},checkChildNodesRecursively:function(e,t,n,r){for(var i,o=0;i=e[o];o++)n(i,t,r)&&r.push({callback:t.callback,elem:i}),i.childNodes.length>0&&l.checkChildNodesRecursively(i.childNodes,t,n,r)},mergeArrays:function(e,t){var n,r={};for(n in e)e.hasOwnProperty(n)&&(r[n]=e[n]);for(n in t)t.hasOwnProperty(n)&&(r[n]=t[n]);return r},toElementsArray:function(t){return n===t||"number"==typeof t.length&&t!==e||(t=[t]),t}}}(),c=function(){var e=function(){this._eventsBucket=[],this._beforeAdding=null,this._beforeRemoving=null};return e.prototype.addEvent=function(e,t,n,r){var i={target:e,selector:t,options:n,callback:r,firedElems:[]};return this._beforeAdding&&this._beforeAdding(i),this._eventsBucket.push(i),i},e.prototype.removeEvent=function(e){for(var t,n=this._eventsBucket.length-1;t=this._eventsBucket[n];n--)if(e(t)){this._beforeRemoving&&this._beforeRemoving(t);var r=this._eventsBucket.splice(n,1);r&&r.length&&(r[0].callback=null)}},e.prototype.beforeAdding=function(e){this._beforeAdding=e},e.prototype.beforeRemoving=function(e){this._beforeRemoving=e},e}(),a=function(t,r){var i=new c,o=this,a={fireOnAttributesModification:!1};return i.beforeAdding(function(n){var i,l=n.target;(l===e.document||l===e)&&(l=document.getElementsByTagName("html")[0]),i=new MutationObserver(function(e){r.call(this,e,n)});var c=t(n.options);i.observe(l,c),n.observer=i,n.me=o}),i.beforeRemoving(function(e){e.observer.disconnect()}),this.bindEvent=function(e,t,n){t=l.mergeArrays(a,t);for(var r=l.toElementsArray(this),o=0;o<r.length;o++)i.addEvent(r[o],e,t,n)},this.unbindEvent=function(){var e=l.toElementsArray(this);i.removeEvent(function(t){for(var r=0;r<e.length;r++)if(this===n||t.target===e[r])return!0;return!1})},this.unbindEventWithSelectorOrCallback=function(e){var t,r=l.toElementsArray(this),o=e;t="function"==typeof e?function(e){for(var t=0;t<r.length;t++)if((this===n||e.target===r[t])&&e.callback===o)return!0;return!1}:function(t){for(var i=0;i<r.length;i++)if((this===n||t.target===r[i])&&t.selector===e)return!0;return!1},i.removeEvent(t)},this.unbindEventWithSelectorAndCallback=function(e,t){var r=l.toElementsArray(this);i.removeEvent(function(i){for(var o=0;o<r.length;o++)if((this===n||i.target===r[o])&&i.selector===e&&i.callback===t)return!0;return!1})},this},s=function(){function e(e){var t={attributes:!1,childList:!0,subtree:!0};return e.fireOnAttributesModification&&(t.attributes=!0),t}function t(e,t){e.forEach(function(e){var n=e.addedNodes,i=e.target,o=[];null!==n&&n.length>0?l.checkChildNodesRecursively(n,t,r,o):"attributes"===e.type&&r(i,t,o)&&o.push({callback:t.callback,elem:i}),l.callCallbacks(o,t)})}function r(e,t){return l.matchesSelector(e,t.selector)&&(e._id===n&&(e._id=o++),-1==t.firedElems.indexOf(e._id))?(t.firedElems.push(e._id),!0):!1}var i={fireOnAttributesModification:!1,onceOnly:!1,existing:!1};f=new a(e,t);var c=f.bindEvent;return f.bindEvent=function(e,t,r){n===r?(r=t,t=i):t=l.mergeArrays(i,t);var o=l.toElementsArray(this);if(t.existing){for(var a=[],s=0;s<o.length;s++)for(var u=o[s].querySelectorAll(e),f=0;f<u.length;f++)a.push({callback:r,elem:u[f]});if(t.onceOnly&&a.length)return r.call(a[0].elem,a[0].elem);setTimeout(l.callCallbacks,1,a)}c.call(this,e,t,r)},f},u=function(){function e(){var e={childList:!0,subtree:!0};return e}function t(e,t){e.forEach(function(e){var n=e.removedNodes,i=[];null!==n&&n.length>0&&l.checkChildNodesRecursively(n,t,r,i),l.callCallbacks(i,t)})}function r(e,t){return l.matchesSelector(e,t.selector)}var i={};d=new a(e,t);var o=d.bindEvent;return d.bindEvent=function(e,t,r){n===r?(r=t,t=i):t=l.mergeArrays(i,t),o.call(this,e,t,r)},d},f=new s,d=new u;t&&i(t.fn),i(HTMLElement.prototype),i(NodeList.prototype),i(HTMLCollection.prototype),i(HTMLDocument.prototype),i(Window.prototype);var h={};return r(f,h,"unbindAllArrive"),r(d,h,"unbindAllLeave"),h}}(window,"undefined"==typeof jQuery?null:jQuery,void 0);


let run = async() => {
  
  console.log("begin run()");
  
  let result = await setAndListen();
  console.log(result);
  
  console.log("end run() <-- this should be the last console.log()");
  
}


let setAndListen = () => new Promise(resolve => {

  console.log("beginning setAndListen()");

  document.arrive(".new", function() {
    
    console.log("new element arrived");
    
    // Using a setTimeout to *simulate* a delay.
    // In the real world, this code would naturally be delayed
    // because the element would take a few seconds to arrive 
    // in the DOM (an http request happens).
    // I'd like for the run() function should finish after 
    // this 2 second delay.
    setTimeout(function(){  
      resolve("returning after 2 second delay");
    }, 2000);

  });

  // Creating an element and adding it to the page.
  let newElement = document.createElement("div");
  newElement.classList.add("new");
  document.body.appendChild(newElement);
  
  console.log("end setAndListen()");

});

run();