isNumeric method

bool isNumeric(
  1. String? s
)

验证是否为纯数字（整数或小数）

Implementation

bool isNumeric(String? s) {
  if (s == null || s.isEmpty) return false;
  const pattern = r'^-?(?:\d+\.?\d*|\.\d+)$';
  return hasMatch(s, pattern);
}