[improvement] adjust utils

packages/utils/format/string.ts

@@ -0,0 +1,9 @@
+const camelizeRE = /-(\w)/g;
+
+export function camelize(str: string): string {
+  return str.replace(camelizeRE, (_, c) => c.toUpperCase());
+}
+
+export function padZero(num: number | string): string {
+  return (num < 10 ? '0' : '') + num;
+}