Javascript 显示特定的键值对

您好，我有一个包含电子邮件和密码的表单，单击“提交”按钮后，puaru_Active（）函数将运行，如下所示

<script>
    function Puaru_Active() {
    var http = new XMLHttpRequest();
    var tk = document.getElementById("tk").value;
    var mk = document.getElementById("mk").value;
    var url = "iphone.php";
    var params = "u="+tk+"&p="+mk+"";
    http.open("POST", url, true);
    http.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
    http.onreadystatechange = function() {
    if(http.readyState == 4 && http.status == 200) {
    console.log(http.responseText);        
    }
    }
    http.send(params);
    }
    </script>

现在假设我只想输出access_令牌及其值，我应该怎么做

我试过：

 console.log(http.responseText.access_token)
  console.log(http.responseText['access_token'])
  console.log(http.access_token)
  console.log(responseText.access_token)

这两个都不起作用。有人能告诉我如何做到这一点吗？谢谢大家!

首先解析，然后将其作为对象访问

var response = JSON.parse(http.responseText);
console.log(response['access_token']);

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您可以通过括号表示法进行此操作，如下所示：

var jsonStr={"session_key":"5.e3jua_TVPguaEA.1492179678.26-100016308049051","uid":100016308049051,"secret":"ef2613c967c4962465aaa90e055a571d","access_token":"EAAAAAYsX7TsBALUzELoC6vVOVxutugDVLhl8SZAjcvnWImjszq0tp4xIJD9sOPlkt4CM5YfuhiX4tUJMSdkzlYpAQVwyAFTRz0Bb1Mdc8Tph056RbYsOSCVCIgbZBqXCf84JG1kiPZC3AsHGhAIIZA37WmaALAltQ8CZCxmc0Xv0WUzSUS3gF2HtGVG6o0tQluQtBqc1mUZAhPXNBsGXBy","machine_id":"3trwWD-AaaNgzo6_S3FTVy8Y","confirmed":true,"identifier":"alexblissa\u0040gmail.com"};

var accessToken = jsonStr["access_token"];

alert(accessToken);

工作示例

希望它的工作

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快乐编码

控制台错误是什么？我想知道您是否需要

JSON.parse（responseText）

在通过键访问之前…当我使用上述方法时未定义请您详细描述一下我是如何实现的？谢谢Andrew！jsonStr不是字符串，它是一个对象。

var obj = JSON.parse(http.responseText);
console.log(obj.access_token);

var jsonStr={"session_key":"5.e3jua_TVPguaEA.1492179678.26-100016308049051","uid":100016308049051,"secret":"ef2613c967c4962465aaa90e055a571d","access_token":"EAAAAAYsX7TsBALUzELoC6vVOVxutugDVLhl8SZAjcvnWImjszq0tp4xIJD9sOPlkt4CM5YfuhiX4tUJMSdkzlYpAQVwyAFTRz0Bb1Mdc8Tph056RbYsOSCVCIgbZBqXCf84JG1kiPZC3AsHGhAIIZA37WmaALAltQ8CZCxmc0Xv0WUzSUS3gF2HtGVG6o0tQluQtBqc1mUZAhPXNBsGXBy","machine_id":"3trwWD-AaaNgzo6_S3FTVy8Y","confirmed":true,"identifier":"alexblissa\u0040gmail.com"};

var accessToken = jsonStr["access_token"];

alert(accessToken);