OnTextChanged called multiple times - autopostback

I have a 50 TextBox of that type:

<asp:TextBox ID="txt_DetImovel0" runat="server"  AutoPostBack="true" OnTextChanged="txt_DetImovel0_TextChanged"></asp:TextBox>
<asp:TextBox ID="txt_DetImovel1" runat="server"  AutoPostBack="true" OnTextChanged="txt_DetImovel0_TextChanged"></asp:TextBox>
<asp:TextBox ID="txt_DetImovel2" runat="server"  AutoPostBack="true" OnTextChanged="txt_DetImovel0_TextChanged"></asp:TextBox>

I have a function in javascript that changes the value of the TextBox when it selects a color (Color Picker)

The problem is that in debug mode I realize that this "txt_DetImovel0_TextChanged" function is being called one for each field! even though .js is only changing 1 field. (I put an alert ('test'), and it only really appears once, but when I debug I see that it is called several times.

Questions:

Is there any way to know or monitor who is firing this function? since in debug mode I only see the actions of the code behind.

How to make only the field that has the value modified by .js actually call this function.?

OBS: I discovered that when I have autopostback = true it will actually send to every field, even though I only changed the value of 1 field !!! Is this a .NET BUG?

The image below shows what cadas textbox does, it is the color picker, every time it changes the color it gets the value.

Complementcodetomakeiteasiertounderstand.ThereisastepthatheassemblessomeJStobetriggeredassoonasyouchangethevalueoftheTextBox:

txt.Append(@"<script type=text/javascript>");
txt.Append("Corescolhe(" + txt_DetImovel0.ClientID + ");");
txt.Append("Corescolhe(" + txt_DetImovel1.ClientID + ");");
txt.Append("Corescolhe(" + txt_DetImovel2.ClientID + ");");
txt.Append("Corescolhe(" + txt_DetImovel3.ClientID + ");");
txt.Append("Corescolhe(" + txt_DetImovel4.ClientID + ");");
txt.Append("Corescolhe(" + txt_DetImovel5.ClientID + ");");
txt.Append("Corescolhe(" + txt_DetImovel6.ClientID + ");");
txt.Append("Corescolhe(" + txt_DetImovel7.ClientID + ");");
txt.Append("Corescolhe(" + txt_DetImovel8.ClientID + ");");
txt.Append("Corescolhe(" + txt_DetImovel9.ClientID + ");");
txt.Append("</script>");

and JS

function Corescolhe(elemento) {
    $(elemento).spectrum({
        showPaletteOnly: false,
        className: "full-spectrum",
        showInitial: true,
        chooseText: "OK",
        cancelText: "cancelar",
        showPalette: true,
        preferredFormat: "hex",
        localStorageKey: "spectrum.demo",
        move: function (color) {
            updateBorders(color);
        },
        hide: function (color) {
            updateBorders(color);
            //  alert('irá mudar');
            $(elemento).val(color);
        }
};

But the problem is that JS really only changes TextBox X but all Textboxes fire the autopostBack at the same time, if I debug it, I see that the txt_DetImovel0_TextChanged function is called once for each component and not for what just changed the value!