If a user checked on the checkbox then the button should be enabled. If not then button should be disabled.
function test(){
if($(this).val() === true){ //not working
$('#send_button').prop('disabled', false);
}
else if($(this).val() === false){
$('#send_button').prop('disabled', true);
}
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/2.2.2/jquery.min.js"></script>
<input id="ischeck" type="checkbox" name="ischeck" value=true>
<label for="ischeck">ischeck</label><br>
<button id="send_button" class="btn btn-primary pull-right" onclick="test()">Send</button>