javascript - 在 ajax/jquery 调用的 success 函数之外使用变量

Question

我有以下代码

var test;

 $.ajax({
    type: "GET",
    url: "../views/person/controller.php?actor=person&action=checkAge",
    data: "age=" + value,
    success: function(msg){
        console.log(msg);
        test = msg; 
    },
});

Validate.fail(test);

现在测试变量应该像控制台所说的那样给出 true 或 false 。但是测试变量给了我未定义的原因？

Answer 1

 var test; // <-- (1) This code runs first  
 $.ajax({  // <-- (2) Then this runs  
    type: "GET",
    url: "../views/person/controller.php?actor=person&action=checkAge",
    data: "age=" + value,
    success: function(msg){
        console.log(msg); //<-- (4) Finally this is run. IF your request is a success 
        test = msg; 
    },
 });
 Validate.fail(test); // <-- (3) This runs third  

查看代码运行的顺序。您的变量此时根本不可用，因为它在通过回调触发代码时运行