jQuery - 等待函数返回值

问题描述

 函数sendMail（from，to，subject，message）
我有一个用于发送带有ajax请求的电子邮件的jquery函数; {
 var datastr =from =+ from +& to =+ to +& subject =+ subject +& message =+ message; 
 $ .ajax（{
 type：POST，
 url：mail.php，
 data：datastr，
 cache：false，
成功：函数（html）{
返回true; 
}，
错误：函数（jqXHR，状态，错误）{
返回false; 
} 
}）; 
} 
  

现在我想告诉用户邮件是否已成功发送或不需要这：

  $（＃feedback）。html（Sending email ...）; 
 if（sendMail（[email protected]，[email protected]，MySubject，MyMessage））
 $（＃feedback）。html（Email sent 。）; 
 else 
 $（＃feedback）。html（Error sending email。）; 
  

但是当然jQuery会在发送邮件之前处理if条件，所以条件为false： - （
）如何让jQuery等到sendMail完成并返回一些内容？

解决方案

虽然给出的答案是有效的，我会考虑保持 sendmail 函数和DOM修改分开（即保持 $（＃feedback）。html ...） code> out of the success / error callbacks）。你可以通过返回 ajax call：



  function sendMail（from，to，subject，message）{
 var datastr =from = + from +& to =+ to +& subject =+ subject +& message =+ message; 
 return $ .ajax（{
 type：POST，
 url：mail.php，
 data：datastr，
 cache：false 
}）; 
} 
  

返回值，所以你可以这样做：



  $（＃feedback） .html（发送电子邮件...）; 
 sendMail（[email protected]，[email protected]，MySubject，MyMessage）
 .done（function（）{
 $（＃feedback ）.html（Email sent。）; 
}）
 .fail（function（）{
 $（＃feedback）。html（Error sending email。） ; 
}）; 
  

请注意，我删除了成功和 error 来自ajax调用的字段，因为它们不是必需的，但如果您需要它们用于其他事情（如日志记录），您仍然可以使用它们。

I have a jquery function for sending email with ajax request;

function sendMail(from,to,subject,message){
    var datastr="from="+from+"&to="+to+"&subject="+subject+"&message="+message;
    $.ajax({
        type: "POST",
        url: "mail.php",
        data: datastr,
        cache: false,
        success: function(html){
            return true;
        },
        error: function(jqXHR,status,error){
            return false;
        }
    });
}

now I want to tell the user if the mail was successfully sent or not like this:

$("#feedback").html("Sending email...");
if(sendMail("[email protected]","[email protected]","MySubject","MyMessage"))
   $("#feedback").html("Email sent.");
else
   $("#feedback").html("Error sending email.");

but of course jQuery processes the if condition before the mail was sent, so the condition is false :-(How do I tell jQuery to wait until sendMail has completed and returns something?

解决方案

While the given answers are valid, I would consider keeping the sendmail function and the DOM modifications separate (i.e. keeping $("#feedback").html... out of the success/error callbacks ). You can do this by returning the result of the ajax call:

function sendMail(from,to,subject,message){
    var datastr="from="+from+"&to="+to+"&subject="+subject+"&message="+message;
    return $.ajax({
        type: "POST",
        url: "mail.php",
        data: datastr,
        cache: false
    });
}

The return value implements the Promise interface, so you can then do this:

$("#feedback").html("Sending email...");
sendMail("[email protected]","[email protected]","MySubject","MyMessage")
    .done(function(){
        $("#feedback").html("Email sent.");
    })
    .fail(function(){
        $("#feedback").html("Error sending email.");
    });

Note that I removed the success and error fields from the ajax call since they're not needed, but you could still use them if you need them for something else, like logging.

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