init

.gitignore

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+dist
+node_modules
+index.html
+.httpserver
+
+package-lock.json
+
+._*
+
+.Spotlight-V100
+.Trashes
+.DS_Store
+.AppleDouble
+.LSOverride
+

.npmignore

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+src/
+test/
+build.js
+.prettierrc.yaml

.prettierrc.yaml

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+
+jsxBracketSameLine: true
+jsxSingleQuote: true
+semi: false
+singleQuote: true
+printWidth: 80
+useTabs: false
+tabWidth: 2
+trailingComma: none
+bracketSpacing: true
+arrowParens: avoid

src/base64.js

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+import { encode, decode } from './helper.js'
+
+// string 转 binary
+export function str2bin(str) {
+  let bin = ''
+  let u8 = encode(str) // 转成Uint8Array
+  for (let i = 0; i < u8.length; i++) {
+    bin += String.fromCharCode(u8[i])
+  }
+  return bin
+}
+
+export function bin2str(b) {
+  let u8 = new Uint8Array(b.length)
+  for (let i = 0; i < u8.length; i++) {
+    u8[i] = b[i].charCodeAt(0)
+  }
+  return decode(u8)
+}
+
+// 支持对中文的base64编码
+export function base64encode(str) {
+  return btoa(str2bin(str))
+}
+
+export function base64decode(str) {
+  return bin2str(atob(str))
+}

src/helper.js

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+const encoder = new TextEncoder()
+const decoder = new TextDecoder()
+
+/**
+ * String 转 Uint8Array
+ */
+export function encode(txt) {
+  return encoder.encode(txt)
+}
+
+/**
+ * Uint8Array 转 String
+ */
+export function decode(u8) {
+  return decoder.decode(u8)
+}
+
+export function getType(val) {
+  return Object.prototype.toString.call(val).slice(8, -1)
+}
+
+export function to16(n) {
+  let p = ''
+  if (n < 16) {
+    p = '0'
+  }
+  return p + n.toString(16)
+}
+
+// 将16进制的文本, 转成uint8array
+export function hex2u8(str) {
+  if (str.length % 2) {
+    throw new Error('Argument str is not a vaild hex string')
+  }
+  let u8 = new Uint8Array(str.length / 2)
+  for (let i = 0; i <= u8.length; i++) {
+    u8[i] = parseInt(str.slice(i * 2, i * 2 + 2), 16)
+  }
+  return u8
+}
+
+/**
+ * 计算二维数组的总长度
+ */
+export function sum(list) {
+  return list.reduce((total, it) => total + it.length, 0)
+}

src/index.js

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+/**
+ * Buffer对象的 polyfill
+ * @author yutent<yutent.io@gmail.com>
+ * @date 2024/05/29 12:29:17
+ */
+
+import { encode, decode, getType, to16, hex2u8, sum } from './helper.js'
+import { base64encode, base64decode, str2bin, bin2str } from './base64.js'
+
+/**
+ * 将其他类型的值, 转为uint8array
+ */
+function any2u8(data = '', encoding = 'utf8') {
+  if (typeof data === 'object') {
+    let type = getType(data)
+
+    switch (type) {
+      case 'Buffer':
+      case 'Uint8Array':
+        return data
+
+      case 'ArrayBuffer':
+        break
+
+      case 'DataView':
+        data = data.buffer
+        break
+    }
+    return new Uint8Array(data)
+  } else {
+    switch (encoding) {
+      case 'base64':
+        data = base64decode(data)
+        break
+
+      case 'hex':
+        return hex2u8(data)
+
+      case 'binary':
+        data = bin2str(data)
+        break
+    }
+
+    return encode(data + '')
+  }
+}
+
+/**
+ * 创建基于Uint8Array的Buffer类
+ */
+export default class Buffer extends Uint8Array {
+  get [Symbol.toStringTag]() {
+    return 'Buffer'
+  }
+
+  static from(data, offsetOrEncoding, end) {
+    let buf = data
+    let start = 0
+    let _encoding = 'utf8'
+
+    if (offsetOrEncoding !== void 0) {
+      if (typeof offsetOrEncoding === 'number') {
+        start = offsetOrEncoding
+      } else if (typeof offsetOrEncoding === 'string') {
+        _encoding = offsetOrEncoding
+      }
+    }
+
+    buf = any2u8(data, _encoding)
+
+    return new Buffer(buf.slice(start, end))
+  }
+
+  static alloc(len, str = '', encoding) {
+    let buf = new Buffer(len)
+    if (str) {
+      buf.fill(str, 0, len, encoding)
+    }
+    return buf
+  }
+
+  static concat(list, encoding) {
+    let len = sum(list)
+    let buf = Buffer.alloc(len)
+
+    let offset = 0
+    for (let it of list) {
+      it.copy(buf, offset)
+      offset += it.length
+    }
+
+    return buf
+  }
+
+  static isBuffer(target) {
+    return getType(target) === 'Buffer'
+  }
+
+  #replace(target, start, end) {
+    for (let i = 0; i < end - start; i++) {
+      this[start + i] = target[i]
+    }
+  }
+
+  toJSON() {
+    return { type: 'Buffer', data: [...this].map(to16) }
+  }
+
+  /**
+   * 这个重构为nodejs版的buf.toString()的功能
+   */
+  toString(encoding = 'utf8', start = 0, end) {
+    let buf = this.slice(start, end)
+
+    switch (encoding) {
+      case 'base64':
+        return base64encode(buf)
+
+      case 'hex':
+        return [...buf].map(to16).join('')
+
+      case 'binary':
+        return str2bin(decode(buf))
+
+      default:
+        return decode(buf)
+    }
+  }
+
+  /**
+   * 原生的 Uint8Array的fill只支持数字,
+   * 这里拓展, 支持字符串和其他Array对象, 与nodejs版相似
+   */
+  fill(val, start = 0, end, encoding = 'utf8') {
+    //
+    end ??= this.length
+
+    if (typeof val === 'number') {
+      super.fill(val, start, end)
+    } else {
+      val = [...any2u8(val, encoding)]
+      if (val.length === 0) {
+        val = [0]
+      }
+      let tmp = val
+
+      while (tmp.length < end - start) {
+        tmp = tmp.concat(val)
+      }
+      tmp = tmp.slice(0, end)
+      this.#replace(tmp, start, end)
+    }
+  }
+
+  /**
+   * 向目标对象中复制内容 (改变的是目标对象, 不是自己)
+   */
+  copy(target, targetStart = 0, sourceStart = 0, sourceEnd) {
+    if (!(target instanceof Buffer)) {
+      throw new TypeError(
+        "copy()'s argument target must be a Buffer Object, but got %s",
+        getType(target)
+      )
+    }
+    sourceEnd ??= this.length
+    // 复制的总长度, 默认等于总长
+    let copied = sourceEnd - sourceStart
+
+    if (copied > 0) {
+      target.#replace(
+        this.slice(sourceStart, sourceEnd),
+        targetStart,
+        targetStart + copied
+      )
+    }
+
+    return copied
+  }
+
+  /**
+   * 在指定位置, 写入指定内容
+   */
+  write(str = '', offset = 0, len, encoding = 'utf8') {
+    len ??= this.length
+    let written = len - offset
+    let end = offset + written
+    let u8 = any2u8(str, encoding)
+
+    if (u8.length < written) {
+      written = u8.length
+      end = offset + written
+    }
+    if (written > 0) {
+      this.#replace(u8, offset, end)
+    }
+    return written
+  }
+}