搜索输入框中，只当用户停止输入后，才进行后续的操作，比如发起Http请求等。
学过电子电路的同学应该知道按键防抖。原理是一样的：就是说当调用动作n毫秒后，才会执行该动作，若在这n毫秒内又调用此动作则将重新计算执行时间。本文将分别探讨在angular.js和vue.js中如何实现对用户输入的防抖。
angular.js中解决方案
把去抖函数写成一个service，方便多处调用：
.factory('debounce', ['$timeout','$q', function($timeout, $q) { // The service is actually this function, which we call with the func // that should be debounced and how long to wait in between calls return function debounce(func, wait, immediate) { var timeout; // Create a deferred object that will be resolved when we need to // actually call the func var deferred = $q.defer(); return function() { var context = this, args = arguments; var later = function() { timeout = null; if(!immediate) { deferred.resolve(func.apply(context, args)); deferred = $q.defer(); } }; var callNow = immediate && !timeout; if ( timeout ) { $timeout.cancel(timeout); } timeout = $timeout(later, wait); if (callNow) { deferred.resolve(func.apply(context,args)); deferred = $q.defer(); } return deferred.promise; }; }; }])
调用方法，在需要使用该功能的controller/directive中注入debounce，也要注入$watch,然后：
$scope.$watch('searchText',debounce(function (newV, oldV) { console.log(newV, oldV); if (newV !== oldV) { $scope.getDatas(newV); } }, 350));
大功告成！
Vue.js中的解决方案
首先在公共函数文件中注册debounce
export function debounce(func, delay) { let timer return function (...args) { if (timer) { clearTimeout(timer) } timer = setTimeout(() => { func.apply(this, args) }, delay) } }
然后在需要使用的组件中引入debounce，并且在created生命周期内调用：
created() { this.$watch('searchText', debounce((newSearchText) => { this.getDatas(newSearchText) }, 200)) }