How to access asp control by ID using javascript function?

Question

I have this asp control in my asp page:

<asp:Content ID="Content3" ContentPlaceHolderID="ContentPlace" runat="server">
    <asp:HiddenField ID="colorBuffer" runat="server" />
</asp:Content>

I use this function to access asp control abouve:

window.onload = function () {
    var elem = document.getElementById("colorBuffer");
}

But elem is always null.Any idea why?I think that some changes made to the name of ID hidden field by ASP.

rjps12 · Accepted Answer · 2016-02-24 09:13:28Z

3

var elem = document.getElementById('<%=colorBuffer.ClientID%>');

answered Feb 24, 2016 at 9:13

rjps12

6057 silver badges15 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Imad · Accepted Answer · 2016-02-24 09:15:34Z

1

document.querySelector('[id^="colorBuffer"]').id;

answered Feb 24, 2016 at 9:15

Imad

7,51014 gold badges64 silver badges124 bronze badges