JavaScript前端开发之实现二进制读写操作

关于javascript前端开发之实现二进制读写操作的相关介绍，请看以下内容详解，本文介绍的非常详细，具有参考价值。

由于种种原因，在浏览器中无法像nodejs那样操作二进制。

最近写了一个在浏览器端操作读写二进制的帮助类

!function (entrance) {
  "use strict";
  if ("object" === typeof exports && "undefined" !== typeof module) {
    module.exports = entrance();
  } else if ("function" === typeof define && define.amd) {
    define([], entrance());
  } else {
    var f;
    if ("undefined" !== typeof window) {
      f = window;
    } else {
      throw new Error('wrong execution environment');
    }
    f.TinyStream = entrance();
  }
}(function () {
  var binaryPot = {
    
    init: function (array) {
      for (var i = 0; i < array.length; i++) {
 array[i] *= 1;
 if (array[i] < 0) {
   array[i] += 256
 }
 if(array[i]>255){
   throw new Error('不合法字节流')
 }
      }
      return array;
    },
    
    writeUTF: function (str, isGetBytes) {
      var back = [],
 byteSize = 0;
      for (var i = 0; i < str.length; i++) {
 var code = str.charCodeAt(i);
 if (code >= 0 && code <= 127) {
   byteSize += 1;
   back.push(code);
 } else if (code >= 128 && code <= 2047) {
   byteSize += 2;
   back.push((192 | (31 & (code >> 6))));
   back.push((128 | (63 & code)))
 } else if (code >= 2048 && code <= 65535) {
   byteSize += 3;
   back.push((224 | (15 & (code >> 12))));
   back.push((128 | (63 & (code >> 6))));
   back.push((128 | (63 & code)))
 }
      }
      for (i = 0; i < back.length; i++) {
 if (back[i] > 255) {
   back[i] &= 255
 }
      }
      if (isGetBytes) {
 return back
      }
      if (byteSize <= 255) {
 return [0, byteSize].concat(back);
      } else {
 return [byteSize >> 8, byteSize & 255].concat(back);
      }
    },
    
    readUTF: function (arr) {
      if (Object.prototype.toString.call(arr) == "[object String]") {
 return arr;
      }
      var UTF = "",
 _arr = this.init(arr);
      for (var i = 0; i < _arr.length; i++) {
 var one = _arr[i].toString(2),
   v = one.match(/^1+?(?=0)/);
 if (v && one.length == 8) {
   var bytesLength = v[0].length,
     store = _arr[i].toString(2).slice(7 - bytesLength);
   for (var st = 1; st < bytesLength; st++) {
     store += _arr[st + i].toString(2).slice(2)
   }
   UTF += String.fromCharCode(parseInt(store, 2));
   i += bytesLength - 1
 } else {
   UTF += String.fromCharCode(_arr[i])
 }
      }
      return UTF
    },
    
    convertStream: function (x) {
      if (x instanceof Stream) {
 return x
      } else {
 return new Stream(x)
      }
    },
    
    toMQttString: function (str) {
      return this.writeUTF(str)
    }
  };
  
  function baseRead(m, i, a) {
    var t = a ? a : [];
    for (var start = 0; start < i; start++) {
      t[start] = m.pool[m.position++]
    }
    return t
  }
  
  var supportArrayBuffer = (function () {
    return !!window.ArrayBuffer;
  })();
  
  function Stream(array) {
    if (!(this instanceof Stream)) {
      return new Stream(array);
    }
    
    this.pool = [];
    if (Object.prototype.toString.call(array) === '[object Array]') {
      this.pool = binaryPot.init(array);
    } else if (Object.prototype.toString.call(array) == "[object ArrayBuffer]") {
      var arr = new Int8Array(array);
      this.pool = binaryPot.init([].slice.call(arr));
    } else if (typeof array === 'string') {
      this.pool = binaryPot.writeUTF(array);
    }
    var self = this;
    //当前流执行的起始位置
    this.position = 0;
    //当前流写入的多少字节
    this.writen = 0;
    //返回当前流执行的起始位置是否已经大于整个流的长度
    this.check = function () {
      return self.position >= self.pool.length
    };
  }
  
  Stream.parse = function (x) {
    return binaryPot.convertStream(x);
  };
  Stream.prototype = {
    
    readInt: function () {
      if (this.check()) {
 return -1
      }
      var end = "";
      for (var i = 0; i < 4; i++) {
 end += this.pool[this.position++].toString(16)
      }
      return parseInt(end, 16);
    },
    
    readByte: function () {
      if (this.check()) {
 return -1
      }
      var val = this.pool[this.position++];
      if (val > 255) {
 val &= 255;
      }
      return val;
    },
    
    read: function (bytesArray) {
      if (this.check()) {
 return -1
      }
      if (bytesArray) {
 return baseRead(this, bytesArray.length | 0, bytesArray)
      } else {
 return this.readByte();
      }
    },
    
    readUTF: function () {
      var big = (this.readByte() << 8) | this.readByte();
      return binaryPot.readUTF(this.pool.slice(this.position, this.position += big));
    },
    
    write: function (_byte) {
      var b = _byte;
      if (Object.prototype.toString.call(b).toLowerCase() == "[object array]") {
 [].push.apply(this.pool, b);
 this.writen += b.length;
      } else {
 if (+b == b) {
   if (b > 255) {
     b &= 255;
   }
   this.pool.push(b);
   this.writen++
 }
      }
      return b
    },
    
    writeChar: function (v) {
      if (+v != v) {
 throw new Error("writeChar:arguments type is error")
      }
      this.write((v >> 8) & 255);
      this.write(v & 255);
      this.writen += 2
    },
    
    writeUTF: function (str) {
      var val = binaryPot.writeUTF(str);
      [].push.apply(this.pool, val);
      this.writen += val.length;
    },
    
    toComplements: function () {
      var _tPool = this.pool;
      for (var i = 0; i < _tPool.length; i++) {
 if (_tPool[i] > 128) {
   _tPool[i] -= 256
 }
      }
      return _tPool
    },
    
    getBytesArray: function (isCom) {
      if (isCom) {
 return this.toComplements()
      }
      return this.pool
    },
    
    toArrayBuffer: function () {
      if (supportArrayBuffer) {
 return new ArrayBuffer(this.getBytesArray());
      } else {
 throw new Error('not support arraybuffer');
      }
    },
    clear: function () {
      this.pool = [];
      this.writen = this.position = 0;
    }
  };
  return Stream;
});

如何使用？

以后，我可以不用为浏览器段处理二进制而发愁了！！！希望本文分享对大家学习javascript二进制相关知识有所帮助。