Question

I’m a newbie in javascript, and I don’t really understand the error I’m having.

I’m working on a MVC3 website, which has to monitor an embedded system.

Here is the javascript code that is running :

function GetTemp() {
    var test = "gTe";
    $.ajax({
        url: '@Url.Action("../Carte/Get")',
        type: 'GET',
        data: {test: test},
        success: function (result) {
            if (result.charAt(4) == 'a') {
                $("#LumAct").text(result.substr(0, 4) + " %");
                alert('a');
            }
    ...

And here is the c# action that returns a string

    public String Get(String test)
    {
        flag = TCPClient.SendData(test);
        if (flag == "1")
        {
            try
            {
                value = TCPClient.ReceiveData();
            }
            catch
            {
                value = "Erreur";
            }
        }
        else value = "Erreur";

        return value;
    }

The error I have is in firebug, which tells me :

TypeError: result.charAt is not a function
        [Stopper sur une erreur]    
if (result.charAt(4) == 'a') {

So, what haven’t I understood? According to me, I’m using an ajx function that sends a httpGet to the controller, which responds with a string. In javascript, I can work on a string like I did.

To use the string object, I haven’t added any library. Should I have done that? I haven’t found any information telling that.

Answer 1

Can you try this:

if (String(result).charAt(4) == 'a') 

Also, as mentioned by @Musa, you should add a dataType attribute to the AJAX call:

$.ajax({
    url: '@Url.Action("../Carte/Get")',
    type: 'GET',
    dataType: 'text',
    data: {test: test},
    success: function (result) {
        if (result.charAt(4) == 'a') {
            $("#LumAct").text(result.substr(0, 4) + " %");
            alert('a');
        }