protobuf.js的结构和webpack的加载之后的结构很相似。这样的模块化组合是个不错的结构方式。1个是适应了不同的加载方式，2个模块直接很独立。webpack的功能更全一点。但如果自己封装js库这样够用了。而且模块对外统一接口 module.exports。这和node很像。

(function(global, undefined) {"use strict";

(functionprelude(modules, cache, entries) {function$require(name) {var $module =cache[name];//没有就去加载

if (!$module)

modules[name][0].call($module = cache[name] ={ exports: {} }, $require, $module, $module.exports);return$module.exports;

}//曝光成全局

var proto = global.proto = $require(entries[0]);//AMD

if (typeof define === "function" &&define.amd) {

define(["long"], function(Long) {if (Long &&Long.isLong) {

proto.util.Long=Long;

proto.configure();

}

});returnproto;

}//CommonJS

if (typeof module === "object" && module &&module.exports)

module.exports=proto;

})//传参

({1: [function(require, module, exports) {functionfirst() {

console.log("first");

}

module.exports=first;

}, {}],2: [function(require, module, exports) {functionsecond() {

console.log("second");

}

module.exports=second;

}],3: [function(require, module, exports) {var proto ={};

proto.first= require(1);

proto.second= require(2);

proto.build= "full";

module.exports=proto;

}]

}, {}, [3]);

})(typeof window==="object"&&window||typeof self==="object"&&self||this)

在处理超过16位的整形就得使用Long.js了。 主要是fromString和toString。

functionfromString(str, unsigned, radix) {if (str.length === 0)throw Error('empty string');if (str === "NaN" || str === "Infinity" || str === "+Infinity" || str === "-Infinity")returnZERO;if (typeof unsigned === 'number') {//For goog.math.long compatibility

radix =unsigned,

unsigned= false;

}else{

unsigned= !!unsigned;

}

radix= radix || 10;if (radix < 2 || 36 0)throw Error('interior hyphen');else if (p === 0) {return fromString(str.substring(1), unsigned, radix).neg();

}//Do several (8) digits each time through the loop, so as to

//minimize the calls to the very expensive emulated div.

var radixToPower = fromNumber(pow_dbl(radix, 8));var result =ZERO;for (var i = 0; i < str.length; i += 8) {var size = Math.min(8, str.length -i),

value= parseInt(str.substring(i, i +size), radix);if (size < 8) {var power =fromNumber(pow_dbl(radix, size));

result=result.mul(power).add(fromNumber(value));

}else{

result=result.mul(radixToPower);

result=result.add(fromNumber(value));

}

}

result.unsigned=unsigned;returnresult;

}

fromstring的思路是把字符串8位一个截取。然后转成Long型(高位，地位，符号位) 加起来。最后是一个Long型。 4294967296 是2的32次方。每次操作之前都会有一个基数的操作 mul(radixToPower)或者mul(power)这两者都是保证result的位数是正确的。

比如{low:123} 和{low:1} 相加之前，先要让{low:123}乘以10，得到{low:1230}再与{low:1}进行位操作。因为第一个是高位，不能直接相加。

functionfromBits(lowBits, highBits, unsigned) {return newLong(lowBits, highBits, unsigned);

}

fromBits 即转为Long对象。value%4294967296 得到低位。/得到高位。结果通过位移合并起来。mul是bit的乘法，add是bit的加法。 原理是讲一个64位的拆成四段。分别16位。this.low左移16位 就得到 low的32-17位是啥。 然后和addend对象的同位相加

最后的合并是通过|运算。位移之后再还原确实很巧妙。一时看上去都不大理解。

LongPrototype.add = functionadd(addend) {if (!isLong(addend))

addend=fromValue(addend);//Divide each number into 4 chunks of 16 bits, and then sum the chunks.

var a48 = this.high >>> 16;var a32 = this.high & 0xFFFF;var a16 = this.low >>> 16;var a00 = this.low & 0xFFFF;var b48 = addend.high >>> 16;var b32 = addend.high & 0xFFFF;var b16 = addend.low >>> 16;var b00 = addend.low & 0xFFFF;var c48 = 0, c32 = 0, c16 = 0, c00 = 0;

c00+= a00 +b00;

c16+= c00 >>> 16;

c00&= 0xFFFF;

c16+= a16 +b16;

c32+= c16 >>> 16;

c16&= 0xFFFF;

c32+= a32 +b32;

c48+= c32 >>> 16;

c32&= 0xFFFF;

c48+= a48 +b48;

c48&= 0xFFFF;return fromBits((c16 << 16) | c00, (c48 << 16) | c32, this.unsigned);

};

>>>和>>有什么区别？？。

toString

LongPrototype.toString = functiontoString(radix) {

radix= radix || 10;if (radix < 2 || 36

if (this.eq(MIN_VALUE)) {//We need to change the Long value before it can be negated, so we remove

//the bottom-most digit in this base and then recurse to do the rest.

var radixLong =fromNumber(radix),

div= this.div(radixLong),

rem1= div.mul(radixLong).sub(this);return div.toString(radix) +rem1.toInt().toString(radix);

}else

return '-' + this.neg().toString(radix);

}//Do several (6) digits each time through the loop, so as to

//minimize the calls to the very expensive emulated div.

var radixToPower = fromNumber(pow_dbl(radix, 6), this.unsigned),

rem= this;var result = '';while (true) {var remDiv =rem.div(radixToPower),

intval= rem.sub(remDiv.mul(radixToPower)).toInt() >>> 0,

digits=intval.toString(radix);

rem=remDiv;if(rem.isZero())return digits +result;else{while (digits.length < 6)

digits= '0' +digits;

result= '' + digits +result;

}

}

};

也是sub之后拼出来的。也就是fromstring的反向操作。