asp.net - Serve Tag not well formed when using EVAL() in OnClientClick event -

i'm trying create onclick event so

onclientclick="document.queryselector('[kpi="31"]').value = '';return false;" 

the kpi= value has data bound, use code so

onclientclick="<%# document.queryselector('[kpi=eval("kpi_id")]').value = '';return false; %>" 

but error saying server code not defined. please..

if datasource collection of objects , requesting property called kpi_id can avoid using eval , use item or container.dataitem.

easiest way me show container.dataitem, since don't know kind of control using bind to. container.dataitem should object, need cast datatype

onclientclick="document.queryselector('[kpi=<%# ((yourdatatype)container.dataitem).kpi_id %>)]').value = '';return false;" 

if use repeater in .net 4.5 can set itemtype repeater datatype can replace ((yourdatatype)container.dataitem) item:

onclientclick="document.queryselector('[kpi=<%# item.kpi_id %>)]').value = '';return false;" 

if not using property object , kpi_id string use actual value, e.g. if it's in datarow, have avoid using " in whole string, without letting compiler know it's not end of attribute. can using ' indicate start , end of attribute , use string.format single quote ' in javascript part of text , compiler knows it's not end of attribute:

onclientclick='<%# string.format("document.queryselector('[kpi={0}]').value = '';  return false;", eval("kpi_id")) %>' 

update: support the additional double quote can do:

onclientclick='<%# string.format("document.queryselector('[kpi=\"{0}\"]').value = '';  return false;", eval("kpi_id")) %>' 

you can replace eval("kpi_id") item.kpi_id or ((yourdatatype)container.dataitem).kpi_id if wanna avoid using eval.