c# - javascript add two textbox values and display in third in asp.net -
how in javascript/asp add 2 textbox values , display in third?
my js code
function sum() { var txtfirstnumbervalue = document.getelementbyid('textbox1').value; var txtsecondnumbervalue = document.getelementbyid('textbox2').value; var result = parseint(txtfirstnumbervalue) + parseint(txtsecondnumbervalue); if (!isnan(result)) { document.getelementbyid('textbox3').value = result; } }
asp in page load
textbox1.attributes.add("onkeyup", "sum();"); textbox2.attributes.add("onkeyup", "sum();");
one thing should know:
by default, asp.net uses auto-generated clientid
property used textbox
control in aspx pages, textbox id become <input id="ctl00_contentplaceholder1_textbox1" type="text" ... />
after rendered. use server control name in client-side need use clientid
this:
function sum() { var txtfirstnumbervalue = document.getelementbyid('<%= textbox1.clientid %>').value; var txtsecondnumbervalue = document.getelementbyid('<%= textbox2.clientid %>').value; var result = parseint(txtfirstnumbervalue) + parseint(txtsecondnumbervalue); if (!isnan(result)) { document.getelementbyid('<%= textbox3.clientid %>').value = result; } }
an alternative avoid using generated clientid
in client-side setting clientidmode
static, here examples use it:
<%-- control level --%> <asp:textbox id="textbox1" runat="server" clientidmode="static" ... /> <%-- placeholder level --%> <asp:content id="content1" runat="server" clientidmode="static" ...>...</asp:content> <%-- page level --%> <%@ page language="c#" clientidmode="static" autoeventwireup="true" ... %>
reference:
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