世界热门:聊聊Vue3 shared模块下38个工具函数（源码阅读）

export function makeMap(  str: string,  expectsLowerCase?: boolean): (key: string) => boolean {  const map: Record = Object.create(null)  const list: Array = str.split(",")  for (let i = 0; i < list.length; i++) {    map[list[i]] = true  }  return expectsLowerCase ? val => !!map[val.toLowerCase()] : val => !!map[val]}

export const EMPTY_OBJ: { readonly [key: string]: any } = __DEV__  ? Object.freeze({})  : {}export const EMPTY_ARR = __DEV__ ? Object.freeze([]) : []

export const NOOP = () => {}

/** * Always return false. */export const NO = () => false

const onRE = /^on[^a-z]/export const isOn = (key: string) => onRE.test(key)

export const isModelListener = (key: string) => key.startsWith("onUpdate:")

export const extend = Object.assign

export const remove = (arr: T[], el: T) => {  const i = arr.indexOf(el)  if (i > -1) {    arr.splice(i, 1)  }}

const hasOwnProperty = Object.prototype.hasOwnPropertyexport const hasOwn = (  val: object,  key: string | symbol): key is keyof typeof val => hasOwnProperty.call(val, key)

export const isArray = Array.isArray

export const isMap = (val: unknown): val is Map =>  toTypeString(val) === "[object Map]"export const isSet = (val: unknown): val is Set =>  toTypeString(val) === "[object Set]"export const isDate = (val: unknown): val is Date =>  toTypeString(val) === "[object Date]"export const isRegExp = (val: unknown): val is RegExp =>  toTypeString(val) === "[object RegExp]"

export const isFunction = (val: unknown): val is Function =>  typeof val === "function"export const isString = (val: unknown): val is string => typeof val === "string"export const isSymbol = (val: unknown): val is symbol => typeof val === "symbol"export const isObject = (val: unknown): val is Record =>  val !== null && typeof val === "object"

export const isPromise = (val: unknown): val is Promise => {  return isObject(val) && isFunction(val.then) && isFunction(val.catch)}

export const objectToString = Object.prototype.toString

export const toTypeString = (value: unknown): string =>  objectToString.call(value)

export const toRawType = (value: unknown): string => {  // extract "RawType" from strings like "[object RawType]"  return toTypeString(value).slice(8, -1)}

export const isPlainObject = (val: unknown): val is object =>  toTypeString(val) === "[object Object]"

export const isIntegerKey = (key: unknown) =>  isString(key) &&  key !== "NaN" &&  key[0] !== "-" &&  "" + parseInt(key, 10) === key

export const isReservedProp = /*#__PURE__*/ makeMap(  // the leading comma is intentional so empty string "" is also included  ",key,ref,ref_for,ref_key," +    "onVnodeBeforeMount,onVnodeMounted," +    "onVnodeBeforeUpdate,onVnodeUpdated," +    "onVnodeBeforeUnmount,onVnodeUnmounted")

export const isBuiltInDirective = /*#__PURE__*/ makeMap(  "bind,cloak,else-if,else,for,html,if,model,on,once,pre,show,slot,text,memo")

const cacheStringFunction =  string>(fn: T): T => {  const cache: Record = Object.create(null)  return ((str: string) => {    const hit = cache[str]    return hit || (cache[str] = fn(str))  }) as T}

const camelizeRE = /-(\w)/g/** * @private */export const camelize = cacheStringFunction((str: string): string => {  return str.replace(camelizeRE, (_, c) => (c ? c.toUpperCase() : ""))})

const hyphenateRE = /\B([A-Z])/g/** * @private */export const hyphenate = cacheStringFunction((str: string) =>  str.replace(hyphenateRE, "-$1").toLowerCase())

/** * @private */export const capitalize = cacheStringFunction(  (str: string) => str.charAt(0).toUpperCase() + str.slice(1))

/** * @private */export const toHandlerKey = cacheStringFunction((str: string) =>  str ? `on${capitalize(str)}` : ``)

// compare whether a value has changed, accounting for NaN.export const hasChanged = (value: any, oldValue: any): boolean =>  !Object.is(value, oldValue)

export const invokeArrayFns = (fns: Function[], arg?: any) => {  for (let i = 0; i < fns.length; i++) {    fns[i](arg)  }}

export const def = (obj: object, key: string | symbol, value: any) => {  Object.defineProperty(obj, key, {    configurable: true,    enumerable: false,    value  })}

/** * "123-foo" will be parsed to 123 * This is used for the .number modifier in v-model */export const looseToNumber = (val: any): any => {  const n = parseFloat(val)  return isNaN(n) ? val : n}

/** * Only conerces number-like strings * "123-foo" will be returned as-is */export const toNumber = (val: any): any => {  const n = isString(val) ? Number(val) : NaN  return isNaN(n) ? val : n}

let _globalThis: anyexport const getGlobalThis = (): any => {  return (    _globalThis ||    (_globalThis =      typeof globalThis !== "undefined"        ? globalThis        : typeof self !== "undefined"        ? self        : typeof window !== "undefined"        ? window        : typeof global !== "undefined"        ? global        : {})  )}

const identRE = /^[_$a-zA-Z\xA0-\uFFFF][_$a-zA-Z0-9\xA0-\uFFFF]*$/export function genPropsAccessExp(name: string) {  return identRE.test(name)    ? `__props.${name}`    : `__props[${JSON.stringify(name)}]`}