AngularJS | ng-change指令

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📜 AngularJS | ng-change指令

📅 最后修改于: 2021-05-13 19:33:44 🧑 作者: Mango

只要输入元素的值发生变化，就会使用AngularJS中的ng-change指令。输入值发生变化时，将立即对表达式求值。它要求存在ng-model指令。只要输入中有任何单个更改，就会触发该事件。它可以与，，<checkbox>和<select>之类的输入元素一起使用。</p> <p><strong>句法：</strong> </p> <div class="hcb_wrap"> <pre class="prism line-numbers lang-python" data-lang="Python"><code class="replace"><element ng-change="expression"> Contents... </element></code></pre> </div> <p>其中，<strong>表达式</strong>是指只要输入值更改就执行的表达式。</p> <p><strong>示例1：</strong>本示例使用ng-change指令通过复选框显示/隐藏某些内容。 </p> <div class="hcb_wrap"> <pre class="prism line-numbers lang-python" data-lang="Python"><code class="replace"><!DOCTYPE html> <html> <head> <title>ng-change Directive</title> <script src= "https://ajax.googleapis.com/ajax/libs/angularjs/1.6.9/angular.min.js"> </script> <script type="text/javascript"> var app = angular.module('geek', []); app.controller('app', function ($scope) { $scope.show = function () { if ($scope.check == true) $scope.result = true; else $scope.result = false; } }); </script> </head> <body style="padding: 30px"> <div ng-app="geek" ng-controller="app"> <h1 style="color:green">GeeksforGeeks</h1> <h2>ng-change Directive</h2> Check to show/hide details <input type="checkbox" ng-change="show()" ng-model="check"> <br><br> <div style="padding:10px; border:1px solid black; width:30%;color:green" ng-show='result'> GeeksforGeeks is the computer science portal for geeks. </div> </div> </body> </html> </code></pre> </div> <p><strong>输出：</strong><br/><strong>在选中复选框之前：</strong> <br/><img alt="ng-change" class="img-fluid" src="https://mangdo-1254073825.cos.ap-chengdu.myqcloud.com//front_eng_imgs/geeksforgeeks2021/AngularJS%20%7C%20ng-change%20Directive_0.jpg"/><br/><strong>选中复选框后：</strong> <br/><img alt="ng-change" class="img-fluid" src="https://mangdo-1254073825.cos.ap-chengdu.myqcloud.com//front_eng_imgs/geeksforgeeks2021/AngularJS%20%7C%20ng-change%20Directive_1.jpg"/></p> <p><strong>示例2：</strong>此示例返回复选框状态更改的次数以及复选框的当前状态。 </p> <div class="hcb_wrap"> <pre class="prism line-numbers lang-python" data-lang="Python"><code class="replace"><!DOCTYPE html> <html> <head> <title>ng-change Directive</title> <script src= "https://ajax.googleapis.com/ajax/libs/angularjs/1.6.9/angular.min.js"> </script> </head> <body ng-app="geek" style="text-align:center"> <h1 style="color:green">GeeksforGeeks</h1> <h2>ng-change Directive</h2> <div ng-controller="prop"> <div> Are you a developer: <input type="checkbox" ng-model="isTrue" ng-change="cnt=cnt+1" ng-init="cnt=0"/> </div> Count: {{cnt}} <pre>{{isTrue}}</pre> </div> <script> var app = angular.module("geek", []); app.controller('prop', ['$scope', function ($app) { $app.isTrue = false; }]); </script> </body> </html> </code></pre> </div> <p><strong>输出：</strong><br/><strong>在选中复选框之前：</strong> <br/><img alt="ng-change" class="img-fluid" src="https://mangdo-1254073825.cos.ap-chengdu.myqcloud.com//front_eng_imgs/geeksforgeeks2021/AngularJS%20%7C%20ng-change%20Directive_2.jpg"/><br/><strong>选中复选框后：</strong> <br/><img alt="ng-change" class="img-fluid" src="https://mangdo-1254073825.cos.ap-chengdu.myqcloud.com//front_eng_imgs/geeksforgeeks2021/AngularJS%20%7C%20ng-change%20Directive_3.jpg"/></p> <div class="_ap_apex_ad" id="82d2079a-8120-480f-9fc7-5cda825d56e7"></div> <p></p></div> </div> </div> </div> </div> </div> <footer> <div class="bg-white text-center pb-1"> <p class="text-body-tertiary pt-3 lh-lg text-opacity-50" id="footer-text">Copyright © 2020 - 2024 版权所有 <br> <a href="https://beian.miit.gov.cn/" target="_blank" class="text-opacity-50 text-body-tertiary mt-1 mb-1">蜀ICP备20006366号-1</a> <br> Made with ❤️ in Chengdu </p> </div> </footer>  <script src="https://unpkg.com/bootstrap@5.3.0-alpha1/dist/js/bootstrap.bundle.min.js" crossorigin="anonymous"></script>  <script src="https://cdn.jsdelivr.net/npm/@meilisearch/instant-meilisearch/dist/instant-meilisearch.umd.min.js"></script> <script src="https://cdn.jsdelivr.net/npm/instantsearch.js@4"></script> <script src="https://www.imangodoc.com/static/javascript/meili_custom.js"></script>  <script src="https://cdn.jsdelivr.net/npm/prismjs@1.29.0/components/prism-core.min.js"></script> <script src="https://cdn.jsdelivr.net/npm/prismjs@1.29.0/plugins/toolbar/prism-toolbar.min.js"></script> <script src="https://cdn.jsdelivr.net/npm/prismjs@1.29.0/plugins/autoloader/prism-autoloader.min.js"></script> <script src="https://cdn.jsdelivr.net/npm/prismjs@1.29.0/plugins/copy-to-clipboard/prism-copy-to-clipboard.min.js"></script> </body> </html>