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AngularJS $applyAsync

Use a supported AngularJS scheduling entry when an external callback changes watched state. $applyAsync queues work and lets the framework coordinate the resulting update instead of forcing a nested digest.

How it works

The native repair action listener belongs to a directive. It schedules the count change through the directive’s scope and removes the listener at destruction. This is a small example of adapting a third-party callback to AngularJS. Prefer a framework-aware API such as $http or $timeout when it already matches the required task, rather than wrapping every ordinary AngularJS handler again.

Run the code

AngularJS 1.8.3 is a legacy framework whose official support ended in January 2022. These examples teach maintenance, not a recommendation for a new application. They need a separate local browser page; Bhylu has no AngularJS playground.

In an empty folder save the HTML below as apply-async.html and the server as lab-server.mjs. Make a vendor folder and save the four pinned libraries there, retaining their MIT notices. With Node 22 or later run node lab-server.mjs apply-async.html, then open http://127.0.0.1:8136/. Stop that lab before running a different lesson. The server supplies fixed read-only HTTP fixtures; no data is saved and it does not connect to SQL. No PHP, Apache or MySQL configuration changes are needed.

Example

apply-async.html

<!doctype html>
<html lang="en" ng-app="repairLab" ng-strict-di>
  <head>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width,initial-scale=1" />
    <title>AngularJS $applyAsync</title>
    <style>
      :root {
        font:
          18px/1.55 system-ui,
          sans-serif;
        color: #0f3464;
        background: #fff;
        color-scheme: light;
      }
      * {
        box-sizing: border-box;
      }
      body {
        margin: 0;
      }
      main {
        max-width: 50rem;
        margin: auto;
        padding: 1.2rem;
      }
      h1 {
        font-size: 1.65rem;
      }
      label {
        display: block;
        margin: 0.6rem 0;
      }
      input,
      select,
      textarea,
      button {
        font: inherit;
        max-width: 100%;
        padding: 0.35rem;
        margin: 0.2rem;
      }
      button {
        border: 1px solid #034fa0;
        border-radius: 0.25rem;
        background: #034fa0;
        color: white;
      }
      button:disabled {
        opacity: 0.55;
      }
      output,
      [role="status"] {
        display: block;
        min-height: 1.5rem;
      }
      table {
        border-collapse: collapse;
        width: 100%;
      }
      td,
      th {
        padding: 0.4rem;
        border: 1px solid #a5bbd4;
        text-align: left;
      }
      pre {
        white-space: pre-wrap;
        overflow-wrap: anywhere;
      }
      :focus-visible {
        outline: 3px solid #0078d4;
        outline-offset: 3px;
      }
      [ng-cloak] {
        display: none !important;
      }
      .marked {
        font-weight: 700;
      }
      .error {
        color: #a02424;
      }
      :root[data-theme="dark"] {
        color: #d6e7fb;
        background: #061d30;
        color-scheme: dark;
      }
      :root[data-theme="dark"] .error {
        color: #ffb4b4;
      }
    </style>
  </head>
  <body>
    <main ng-controller="DeskController as vm" ng-cloak>
      <h1>Community repair desk</h1>
      <p>AngularJS 1.8.3 · Legacy maintenance lab · Local demonstration</p>
      <button type="button" scheduled-change>Record external action</button>
      <p data-result>{{ vm.count }} actions</p>
    </main>
    <script src="/vendor/angular.min.js"></script>
    <script>
      (function () {
        "use strict";
        var app = angular.module("repairLab", []);
        app.directive("scheduledChange", [
          function () {
            return {
              link: function (scope, element) {
                function change() {
                  scope.$applyAsync(function () {
                    scope.vm.count += 1;
                  });
                }
                element.on("click", change);
                scope.$on("$destroy", function () {
                  element.off("click", change);
                });
              },
            };
          },
        ]);
        app.controller("DeskController", [
          function () {
            var vm = this;
            vm.count = 0;
          },
        ]);
      })();
    </script>
  </body>
</html>
Focus on the bindings and controller

This excerpt leaves out the document shell, styles and library files. Use the complete download to run it.


<button type="button" scheduled-change>Record external action</button>
<p data-result>{{ vm.count }} actions</p>
<script>
  (function () {
    "use strict";
    var app = angular.module("repairLab", []);
    app.directive("scheduledChange", [
      function () {
        return {
          link: function (scope, element) {
            function change() {
              scope.$applyAsync(function () {
                scope.vm.count += 1;
              });
            }
            element.on("click", change);
            scope.$on("$destroy", function () {
              element.off("click", change);
            });
          },
        };
      },
    ]);
    app.controller("DeskController", [
      function () {
        var vm = this;
        vm.count = 0;
      },
    ]);
  })();
</script>

Expected result

0 actions

The click produces one action without needing a separate refresh button. The browser review observes the bound text after the scheduled update. Scheduling does not validate the value or make an external operation transactional; it only establishes the framework’s update entry.

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