refactor: use faster key check

packages/shared/src/index.ts

@@ -2,9 +2,11 @@ export const EMPTY_OBJ: { readonly [key: string]: any } = Object.freeze({})
 
 export const NOOP = () => {}
 
-export const onRE = /^on/
 export const reservedPropRE = /^(?:key|ref|slots)$|^vnode/
 
+export const isOn = (key: string) => key[0] === 'o' && key[1] === 'n'
+export const isReservedKey = (key: string) => key[0] === '_' || key[0] === '$'
+
 export const isArray = Array.isArray
 export const isFunction = (val: any): val is Function =>
   typeof val === 'function'