JSON Array Not Decoding With Eval

Question

I have two files, one containing an array in PHP that is echoed via json_encode, and the other full of javascript functions for a webpage. One such function, that looks like this (and is unfinished):

/*
 * Function: selectVictim
 * Called from function laserOn()
 *
 * Selects a random victim from a list of victims
 *
 * @return String: victim
 */
function selectVictim()
{
var params = "url=queenofsheep.com/Sheep/victims.php";
var request = new ajaxRequest();

request.open("POST", "victims.php", true);
request.setRequestHeader("Content-Type",
                             "application/x-www-form-urlencoded");
request.setRequestHeader("Content-Length", params.length);
request.setRequestHeader("Connection", "close");

request.onreadystatechange = function ()
{
    if (this.readyState == 4)
    {
        if (this.status == 200)
        {
            if (this.responseText != null )
            {
                var vicString = this.responseText;
                var vicArray = eval('"'+vicString+'"');
                //var vicArray = vicString.split(',');
                //var numVic = Math.floor(Math.random() * (vicArray - 1));
                alert(vicArray);
            }
            else alert("Ajax error: No data received");
        }
        else alert("Ajax Error: " + this.statusText);
    }
}

request.send(params);
}

Is supposed to take in the array from the other file and do things to it that are beyond the scope of this question. Unfortunately, while this.responseText contains a JSON encoded array of the format

var jsonArr = 
     ["1","2,","3"]

activating the function does nothing, and evaling this.responseText yields "undefined."

What am I doing wrong here? I can provide more examples of the real code, the actual array, whatever, if need be. This is driving me crazy.

Answer 1

Use request instead of this. this refers to the window object.

Edit: if var jsonArr=[1, 2, 3]; is literally the response, you should use eval(vicString+';jsonArr'); if you can't alter the response text.

If you'd run 'eval("var test=[1,2,3];")', you'ld have seen that it indeed returns undefined. But this isn't a good practice in using JSON.

Answer 2

Try adding "(" and ")" to the Eval Function. That's how I've seen it done in the past

var myObject = eval('(' + vicString + ')');

Answer 3

Set the content type of the response in the server to "application/json" and you won't have to use eval anymore.
Also you would be better of using an ajax framework instead of using your own ajax functions.