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AngularJS Isolate Scope

An isolate scope gives a reusable directive an explicit binding contract instead of inheriting arbitrary parent fields. It is different from a normal child scope that inherits through the scope hierarchy.

How it works

The repair label receives text through an @ binding. Its template reads only its own label property, while the caller owns the selected text. Changing the parent updates that declared input. Other bindings such as = and & express different relationships; an isolate scope alone does not decide which model should own an edit.

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 isolate-scope.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 isolate-scope.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

isolate-scope.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 Isolate Scope</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>
      <repair-label label="{{ vm.label }}"></repair-label
      ><button type="button" ng-click="vm.label='Latch check'">
        Change label
      </button>
    </main>
    <script src="/vendor/angular.min.js"></script>
    <script>
      (function () {
        "use strict";
        var app = angular.module("repairLab", []);
        app.directive("repairLabel", [
          function () {
            return {
              restrict: "E",
              scope: { label: "@" },
              template: "<p data-result>{{ label }}</p>",
            };
          },
        ]);
        app.controller("DeskController", [
          function () {
            var vm = this;
            vm.label = "Hinge check";
          },
        ]);
      })();
    </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.


<repair-label label="{{ vm.label }}"></repair-label
><button type="button" ng-click="vm.label='Latch check'">Change label</button>
<script>
  (function () {
    "use strict";
    var app = angular.module("repairLab", []);
    app.directive("repairLabel", [
      function () {
        return {
          restrict: "E",
          scope: { label: "@" },
          template: "<p data-result>{{ label }}</p>",
        };
      },
    ]);
    app.controller("DeskController", [
      function () {
        var vm = this;
        vm.label = "Hinge check";
      },
    ]);
  })();
</script>

Expected result

Hinge check

The view first shows Hinge check and then Latch check. The update travels through a declared binding rather than an implicit parent lookup. For a new view boundary inside maintained AngularJS code, a component often gives a simpler default contract than a highly configurable custom directive.

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