访问JSON文件的问题？

Question

Here is my test.json file

{
"pageTitle": "Test Page",
"firstName": "Matt"
}

Here is how I'm accessing it in my JS file

var jsonObj = {};
var ajaxReq = new XMLHttpRequest();
ajaxReq.overrideMimeType("application/json");
ajaxReq.open('GET', 'path/to/file/test.json', true);
ajaxReq.onreadystatechange = function () 
{
    if (ajaxReq.readyState == 4) 
    {
        jsonObj = ajaxReq.responseText;
        alert(jsonObj.pageTitle);
    }
}
ajaxReq.send(null);

But when I run the script the alert box says 'undefined'. Can anyone please tell me what I'm doing wrong here? I've been working at this for a couple hours now and can't seem to find the answer. Thank you for any help.

Answer 1

The responseText property refers to a string, containing the response text. It doesn't contain a JavaScript object, and therefore doesn't have a pageTitle property.

Since the string is in the JSON format, it can be easily parsed into an object with the JSON.parse method:

jsonObj = JSON.parse(ajaxReq.responseText);

Answer 2

update jsonObj = ajaxReq.responseText; to follow line,please try!

jsonObj = eval('(' + ajaxReq.responseText + ')');