angular.js和vue.js中實現函數去抖（debounce）

問題描述

搜索輸入框中，只當用戶中止輸入後，才進行後續的操做，好比發起Http請求等。

學過電子電路的同窗應該知道按鍵防抖。原理是同樣的：就是說當調用動做n毫秒後，纔會執行該動做，若在這n毫秒內又調用此動做則將從新計算執行時間。本文將分別探討在angular.js和vue.js中如何實現對用戶輸入的防抖。

angular.js中解決方案

把去抖函數寫成一個service，方便多處調用：

.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;
      };
    };
  }])

調用方法，在須要使用該功能的controller/directive中注入debounce，也要注入$watch,而後：

$scope.$watch('searchText',debounce(function (newV, oldV) {
   console.log(newV, oldV);
   if (newV !== oldV) {
       $scope.getDatas(newV);
   }
}, 350));

大功告成！

Vue.js中的解決方案

首先在公共函數文件中註冊debounce

export function debounce(func, delay) {
  let timer

  return function (...args) {
    if (timer) {
      clearTimeout(timer)
    }
    timer = setTimeout(() => {
      func.apply(this, args)
    }, delay)
  }
}

而後在須要使用的組件中引入debounce，而且在created生命週期內調用：

created() {
  this.$watch('searchText', debounce((newSearchText) => {
    this.getDatas(newSearchText)
  }, 200))
}

大功告成！

引用

1. https://stackoverflow.com/questions/29771011/angularjs-watch-with-debounce
2. https://www.cnblogs.com/fsjohnhuang/p/4147810.html