Javascript append to variable data echoed back from php

Question

I have this lines of code placed inside an app i am currently developing. I send to the url the valdat variable which is then processed through a php file and then echoed back to the app. How can i append to a variable x the data the alert message displays?

var valdat="foo";

$.ajax({
   url: 'http://www.link./file.php',
   type: 'POST',
   data: {
     valdat:valdat

   },

   error: function(data) {
   alert(data);

   },

   success: function(data) {
   alert(data);
},

});

Answer 1

If you mean append the returning value directly to a known variable you can just use += :

var valdat  ="foo";
var x       = "Something";

$.ajax({
   url: 'http://www.link./file.php',
   type: 'POST',
   data: {
     valdat:valdat

   },

   error: function(data) {
        x += data; 

        alert(x); //Will output "Something" + the content of `data`

   },

   success: function(data) {
        x += data; 

        alert(x); //Will output "Something" + the content of `data`
    },

});

Answer 2

解决了它... ajax调用正在异步执行，这意味着它与JS的其余部分并行运行，这意味着编译器将执行以下操作：1）valdat = foo 2）x = bar 3）h = x 4） ajax调用，所以程序不知道x是谁，因为它直到结尾都没有一个https://stackoverflow.com/a/5936026/5467736