用于将多个Jquery就绪函数组合成单个就绪函数的繁重任务

// 创建多个Deferred对象
var deferred1 = $.Deferred();
var deferred2 = $.Deferred();
var deferred3 = $.Deferred();

// 定义多个异步操作
setTimeout(function() {
  deferred1.resolve("Deferred 1 resolved");
}, 2000);

setTimeout(function() {
  deferred2.resolve("Deferred 2 resolved");
}, 3000);

setTimeout(function() {
  deferred3.resolve("Deferred 3 resolved");
}, 4000);

// 使用$.when()组合多个Deferred对象
$.when(deferred1, deferred2, deferred3).done(function(result1, result2, result3) {
  // 在所有Deferred对象都变为resolved状态时触发回调函数
  console.log(result1); // 输出："Deferred 1 resolved"
  console.log(result2); // 输出："Deferred 2 resolved"
  console.log(result3); // 输出："Deferred 3 resolved"
});