JSFiddle - React, Tailwind, and code Playground
by Alfie
HTML
<div class="span1">
<input type="checkbox" value="l4" id="l4" field="" defaultValue="" appEditor="true"/>
</div>
<div class="span7">
<input type="text" class="m-wrap span10" id="fld_l4" defaultValue="" editType="intEdit" appEditor="true" disabled />
</div>
JavaScript
$('#l4').on('click',function(){
$('#fld_l4').prop('disabled',!this.checked);
});