使用JQuery在循环中在Ajax请求之前发出警报

IMO

jQuery.Deferred()

• Deferred对象是

  chainable utility

  通过调用jQuery.Deferred（）方法创建的对象。它可以将多个回调注册到回调队列中，调用回调队列，并中继任何同步或异步功能的成功或失败状态。

• deferred objects

  可用于处理异步事件-您启动一个动作，然后注册一个回调，该回调将在动作完成时调用。这包括AJAX，尽管还有很多其他用途。

哪里要求解决

function callAjaxMethod(url, step) {  return $.Deferred(function() {        //Confirm box for use inputs        if(confirm(step))        {          //Ajax call$.ajax(url).done(function(data){  //Do something  //Update your HTML if needed});        }        setTimeout(function() {          //This will resolve your call again          this.resolve();        }.bind(this), 1000);  })}

递延对象

var defer = $.Deferred().resolve();var counters = [1, 2, 3, 4, 5];$.each(counters, function(key, value) {    defer = defer.then(function() {      return callAjaxMethod('URL', value);    });});

完成后它将调用

defer.then(function() {  //It will call when all done});

很少的文档

官方jQuery.Deferred

通过jQuery
deferred的调用ajax

关于多个jQuery Promise的文章

希望这对您有帮助:)

var $demo = $('#demo');var ajaxURL = 'https://jsonplaceholder.typipre.com/posts';function callAjaxMethod(url, step) {  return $.Deferred(function() {        //Confirm box for user inputs        if(confirm(step))        {          //Ajax call          $.ajax(url).done(function(data){ //Do something //console.log(data); //Update the HTML OK $demo.append(step + ": Success" + "<br/>");          });        }        else        {          //Update the HTML when cancel          $demo.append("<font color='red'>"+ step +": Cancelled </font>" + "<br/>");        }        //Use timeout to get the resolved        setTimeout(function() {          this.resolve();        }.bind(this), 1000);  })}//Defer objectvar defer = $.Deferred().resolve();var counters = ['call 1', 'call 2', 'call 3', 'call 4', 'call 5'];//Loop your calls$.each(counters, function(key, value) {    defer = defer.then(function() {      return callAjaxMethod(ajaxURL, value);    });});defer.then(function() {  //It will call when all done  $(demo).append("<br/><br/>"+"ALL DONE");});div{  color: blue;  font-size: 14px;}<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script><div id="demo"></div>