var re=/\b.*?(left:\s*-?\d+\.?\d*px;)/igm;
function matchIt(str) {
repl = str.replace(re, function($0, $1) {
return $0 == $1? $0 : '';
});
return repl !== ""? true : false;
}
print(matchIt('margin-left:100px;')); // false
print(matchIt('left:100px;')); // true
dmFyIHJlPS9cYi4qPyhsZWZ0OlxzKi0/XGQrXC4/XGQqcHg7KS9pZ207CgpmdW5jdGlvbiBtYXRjaEl0KHN0cikgewogICByZXBsID0gc3RyLnJlcGxhY2UocmUsIGZ1bmN0aW9uKCQwLCAkMSkgewogICAgICByZXR1cm4gJDAgPT0gJDE/ICQwIDogJyc7CiAgIH0pOwogICByZXR1cm4gcmVwbCAhPT0gIiI/IHRydWUgOiBmYWxzZTsKfQoKcHJpbnQobWF0Y2hJdCgnbWFyZ2luLWxlZnQ6MTAwcHg7JykpOyAvLyBmYWxzZQpwcmludChtYXRjaEl0KCdsZWZ0OjEwMHB4OycpKTsgLy8gdHJ1ZQ==