基于ts重构axios

ustbhuangyi 老师的基于TypeScript从零重构axios学习记录。

知识点

TypeScript 常用语法：

基础类型 、 函数 、 变量声明 、 接口 、 类 、 泛型 、 类型推新 、 高级类型

axios js库：

项目脚手架 、 基础功能实现 、 异常情况处理 、 接口扩展 、 拦截器实现 、 配置化实现 、 取消功能实现 、 其他功能实现等等

主要工具：
Jest 、 TSLint 、 Commitizen 、 Prettier 、 RollupJS 、 Semantic release

基本语法#

点我

需求分析#

Features#

在浏览器使用 XMLHttpRequest 对象通讯
支持 Promise API
支持请求和响应的拦截器
支持请求数据和响应数据的转换
支持请求的取消
JSON数据的自动转换
客户端防止 XSRF

基于 XMLHttpRequest 编写基本请求代码#

处理请求数据：url/body/headers#

src/types/index.ts

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export type Method = 'get' | 'GET' | 'delete' | 'Delete' | 'head' | 'HEAD' | 'options' | 'OPTIONS' | 'post' | 'POST' | 'put' | 'PUT' | 'patch' | 'PATCH'
export interface AxiosRequestConfig {
  url: string
  method?: Method
  data?: any
  params?: any
  headers?: any
}

src/xhr.ts

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import { AxiosRequestConfig } from './types'

export default function xhr(config: AxiosRequestConfig): void {
  const { data = null, url, method = 'get', headers } = config
  const request = new XMLHttpRequest()
  // method,url,async
  request.open(method.toUpperCase(), url, true)
  Object.keys(headers).forEach(name => {
    if (data === null && name.toLowerCase() === 'content-type') {
      delete headers[name]
    } else {
      request.setRequestHeader(name, headers[name])
    }
  })
  request.send(data)
}

src/index.ts

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import { AxiosRequestConfig } from './types'
import { buildURL } from './helpers/url';
import { transformRequest } from './helpers/data';
import xhr from './xhr'
import { processHeaders } from './helpers/header';

function axios(config: AxiosRequestConfig): void {
  processConfig(config)
  xhr(config)
}

function processConfig(config: AxiosRequestConfig): void {
  config.url = transformURL(config)
  config.data = transformRequestData(config)
  config.headers = transformHeaders(config)
}

function transformHeaders(config: AxiosRequestConfig): void {
  const { headers = {}, data } = config
  return processHeaders(headers, data)
}

function transformRequestData(config: AxiosRequestConfig): void {
  return transformRequest(config.data)
}

function transformURL(config: AxiosRequestConfig): string {
  const { url, params } = config;
  return buildURL(url, params)
}

export default axios

工具类#

data.ts

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import { isPlainObject } from "./util";

export function transformRequest(data: any): any {
  if (isPlainObject(data)) {
    return JSON.stringify(data)
  }
  return data
}

headers.ts

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import { isPlainObject } from "./util"

function normalizeHeaderName(headers: any, normalizedName: string): void {
  if (!headers) {
    return
  }
  Object.keys(headers).forEach(name => {
    if (name !== normalizedName && name.toUpperCase() === normalizedName.toUpperCase()) {
      headers[normalizedName] = headers[name]
      delete headers[name]
    }
  })
}

export function processHeaders(headers: any, data: any): any {
  normalizeHeaderName(headers, 'Content-Type')
  if (isPlainObject(data)) {
    if (headers && !headers['Content-Type']) {
      headers['Content-Type'] = 'application/json;charset=utf-8'
    }
  }
  return headers
}

url.ts

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import { isDate, isPlainObject } from './util'

function encode(val: string): string {
  return encodeURIComponent(val)
    .replace(/%40/g, '@')
    .replace(/%3A/ig, ':')
    .replace(/%24/g, '**util.ts**

```tsx
const toString = Object.prototype.toString

export function isDate(val: any): val is Date {
  return toString.call(val) === '[object Date]'
}

export function isPlainObject(val: any): val is Object {
  return toString.call(val) === '[object Object]'
}

处理响应数据#

定义响应接口

types/index

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export interface AxiosResponse {
  data: any
  status: number
  statusText: string
  headers: any
  config: AxiosRequestConfig
  request: any
}
export interface AxiosPromise extends Promise<AxiosResponse> {

}

处理 headers 的数据

helpers/header.ts

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export function processHeaders(headers: any, data: any): any {
  normalizeHeaderName(headers, 'Content-Type')
  if (isPlainObject(data)) {
    if (headers && !headers['Content-Type']) {
      headers['Content-Type'] = 'application/json;charset=utf-8'
    }
  }
  return headers
}

export function parseHeaders(headers: string): any {
  let parsed = Object.create(null)
  if (!headers) {
    return headers
  }
  headers.split('\r\n').forEach(line => {
    let [key, val] = line.split(':')
    key = key.trim().toLowerCase()
    if (!key) {
      return
    }
    if (val) {
      val = val.trim();
    }
    parsed[key] = val
  })
  return parsed
}

处理响应data

helpers/data.ts

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export function transformResponse(data: any): any {
  if (typeof data === 'string') {
    try {
      data = JSON.parse(data)
    } catch (e) {
      // do nothing
    }
  }
  return data
}

修改 xhr, 返回一个 Promise

xhr.ts

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import { AxiosRequestConfig, AxiosPromise, AxiosResponse } from './types'
import { parseHeaders } from './helpers/headers'

export default function xhr(config: AxiosRequestConfig): AxiosPromise {
  return new Promise(resolve => {
    const { data = null, url, method = 'get', headers, responseType } = config
    const request = new XMLHttpRequest()
    if (responseType) {
      request.responseType = responseType
    }
    // method,url,async
    request.open(method.toUpperCase(), url, true)

    request.onreadystatechange = function handleLoad() {
      if (request.readyState !== 4) {
        return
      }

      const responseHeaders = parseHeaders(request.getAllResponseHeaders())
      const responseData = responseType && responseType !== 'text' ? request.response : request.responseText
      const response: AxiosResponse = {
        data: responseData,
        status: request.status,
        statusText: request.statusText,
        headers: responseHeaders,
        config,
        request
      }
      resolve(response)
    }
    Object.keys(headers).forEach(name => {
      if (data === null && name.toLowerCase() === 'content-type') {
        delete headers[name]
      } else {
        request.setRequestHeader(name, headers[name])
      }
    })
    request.send(data)
  })

}

具体代码地址

)

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.replace(/%2C/ig, ',')
.replace(/%20/g, '+')
.replace(/%5B/ig, '[')
.replace(/%5D/ig, ']')

}

export function buildURL(url: string, params?: any): string {
if (!params) {

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return url

}
const parts: string[] = []
Object.keys(params).forEach(key => {

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const val = params[key]
if (val === null || typeof val === 'undefined') {
  return
}
let values = []
if (Array.isArray(val)) {
  values = val
  key += '[]'
} else {
  values = [val]
}
values.forEach(val => {
  if (isDate(val)) {
    val = val.toISOString()
  } else if (isPlainObject(val)) {
    val = JSON.stringify(val)
  }
  parts.push( `${encode(key)}=${encode(val)}` )
})

})
let serializedParams = parts.join('&')
if (serializedParams) {

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const markIndex = url.indexOf('#')
if (markIndex !== -1) {
  url = url.slice(0, markIndex)
}
url += (url.indexOf('?') === -1 ? '?' : '&') + serializedParams

}
return url
}

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**util.ts**

```tsx
const toString = Object.prototype.toString

export function isDate(val: any): val is Date {
  return toString.call(val) === '[object Date]'
}

export function isPlainObject(val: any): val is Object {
  return toString.call(val) === '[object Object]'
}