# is 类型判断工具函数 / Type checking utility functions ## Overview / 概述 提供一系列类型判断函数，用于在运行时检测变量的类型。Provide a series of type checking functions for runtime type detection. ## Functions ### isDef 判断不是 undefined / Check if not undefined ```ts function isDef(val?: T): val is T ``` **Parameters / 参数** | Name | Type | Description | |------|------|-------------| | `val` | `T \| undefined` | 要检测的值 | **Returns / 返回值** - `val is T`: 如果值不是 undefined，返回 true **Example / 示例** ```ts isDef('test') // true isDef(undefined) // false isDef(null) // true (null is not undefined) ``` --- ### isUnDef 判断是 undefined / Check if undefined ```ts function isUnDef(val?: T): val is T ``` **Example / 示例** ```ts isUnDef(undefined) // true isUnDef('test') // false ``` --- ### isObject 判断是 Object（含数组、Map）/ Check if is Object (includes Array, Map) ```ts function isObject(val: any): val is Record ``` **Example / 示例** ```ts isObject({}) // true isObject([]) // true isObject(new Map()) // true isObject(null) // false isObject('string') // false ``` --- ### isPlainObject 判断是原始 Object（不含数组）/ Check if is plain Object ```ts function isPlainObject(val: unknown): val is Record ``` **Example / 示例** ```ts isPlainObject({}) // true isPlainObject({ a: 1 }) // true isPlainObject([]) // false isPlainObject(new Map()) // false ``` --- ### isEmpty 判断是空（含空数组、空对象、空 Map）/ Check if is empty ```ts function isEmpty(val: T): val is T ``` **Example / 示例** ```ts isEmpty([]) // true isEmpty({}) // true isEmpty(new Map()) // true isEmpty(new Set()) // true isEmpty('') // true isEmpty([1, 2]) // false isEmpty({ a: 1 }) // false ``` --- ### isEmptyValue 检测是否空值（空 string/undefined/null）/ Check if is empty value ```ts function isEmptyValue(val: string | number | null | undefined): boolean ``` **Example / 示例** ```ts isEmptyValue('') // true isEmptyValue(null) // true isEmptyValue(undefined) // true isEmptyValue('test') // false isEmptyValue(0) // false ``` --- ### isDate 判断是日期对象 / Check if is Date object ```ts function isDate(val: unknown): val is Date ``` **Example / 示例** ```ts isDate(new Date()) // true isDate('2024-01-01') // false isDate(Date.now()) // false ``` --- ### isNullOrUnDef 判断是 null 或 undefined / Check if is null or undefined ```ts function isNullOrUnDef(val: unknown): val is null | undefined ``` **Example / 示例** ```ts isNullOrUnDef(null) // true isNullOrUnDef(undefined) // true isNullOrUnDef('') // false isNullOrUnDef(0) // false ``` --- ### isNumber 是否是 number / Check if is number ```ts function isNumber(val: unknown): val is number ``` **Example / 示例** ```ts isNumber(123) // true isNumber('123') // false isNumber(NaN) // true isNumber(Infinity) // true ``` --- ### isInteger 判断是否为整数（支持负数）/ Check if is integer ```ts function isInteger(val: unknown): boolean ``` **Example / 示例** ```ts isInteger(123) // true isInteger('123') // true isInteger(-456) // true isInteger('3.14') // false isInteger(3.14) // false isInteger('') // false ``` --- ### isNumeric 判断是否为数值（整数或小数）/ Check if is numeric ```ts function isNumeric(val: unknown): boolean ``` **Example / 示例** ```ts isNumeric(123) // true isNumeric('123') // true isNumeric('3.14') // true isNumeric(-456.78) // true isNumeric('abc') // false ``` --- ### isPromise 是否是 Promise / Check if is Promise ```ts function isPromise(val: any): val is Promise ``` **Example / 示例** ```ts isPromise(Promise.resolve()) // true isPromise(async () => {}) // true isPromise({ then: () => {} }) // true (duck typing) isPromise('test') // false ``` --- ### isFunction 是否是函数 / Check if is function ```ts function isFunction(val: unknown): val is Function ``` **Example /示例** ```ts isFunction(() => {}) // true isFunction(class {}) // true isFunction(function(){})// true isFunction('test') // false ``` --- ### isArray 是否是数组 / Check if is array ```ts function isArray(val: any): val is Array ``` **Example / 示例** ```ts isArray([]) // true isArray(new Array()) // true isArray({ length: 0 })// false isArray('test') // false ``` --- ### isUrl 是否是 URL / Check if is URL ```ts function isUrl(path: string): boolean ``` **Parameters / 参数** | Name | Type | Description | |------|------|-------------| | `path` | `string` | 要检测的字符串 | **Returns / 返回值** - `boolean`: 如果是有效的 URL 返回 true **Example / 示例** ```ts isUrl('http://www.baidu.com') // true isUrl('https://example.com') // true isUrl('/api/user') // true isUrl('not-a-url') // false ``` --- ### isWindow 是否是 Window / Check if is Window ```ts function isWindow(val: any): val is Window ``` **Example / 示例** ```ts isWindow(window) // true (in browser) isWindow(document) // false isWindow({}) // false ``` --- ### isMap 是否是 Map / Check if is Map ```ts function isMap(val: unknown): val is Map ``` **Example / 示例** ```ts isMap(new Map()) // true isMap({}) // false isMap([]) // false ``` --- ### isRegExp 是否是正则 / Check if is RegExp ```ts function isRegExp(val: unknown): val is RegExp ``` **Example / 示例** ```ts isRegExp(/test/) // true isRegExp(new RegExp('test')) // true isRegExp('test') // false ``` --- ## Use Cases / 使用场景 ### 表单验证 / Form Validation ```ts function validateValue(value: unknown) { if (isEmptyValue(value)) { return 'Value is required' } if (!isString(value) && !isNumber(value)) { return 'Invalid value type' } return null } ``` ### 数据处理 / Data Processing ```ts function processData(data: unknown) { if (isPlainObject(data)) { // 处理普通对象 } else if (isArray(data)) { // 处理数组 } else if (isDate(data)) { // 处理日期 } } ``` ### 类型守卫 / Type Guards ```ts function handleValue(value: string | number | Date) { if (isDate(value)) { // TypeScript knows value is Date here return value.getTime() } // TypeScript knows value is string | number here return value } ```