select all checkbox rails
$(document).ready(function(){
$('#check_all').on("click", function() {
// grouping all the checkbox using the classname
var checkboxes = $("class name for the checkbox");
// check whether checkboxes are selected.
if(checkboxes.prop("checked")){
// if they are selected, unchecking all the checkbox
checkboxes.prop("checked",false);
} else {
// if they are not selected, checking all the checkbox
checkboxes.prop("checked",true);
}
});
});