在这种情况下，我建议您使用CryptoJS。

基本上，CryptoJS是一个使用最佳实践和模式在JavaScript中实现的标准和安全加密算法的不断增长的集合。它们速度快，界面一致且简单。

因此，如果你想计算密码字符串的MD5哈希值，那么按照以下步骤进行:

<script src="https://cdnjs.cloudflare.com/ajax/libs/crypto-js/3.1.9-1/core.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/crypto-js/3.1.9-1/md5.js"></script>
<script>
    var passhash = CryptoJS.MD5(password).toString();

    $.post(
      'includes/login.php', 
      { user: username, pass: passhash },
      onLogin, 
      'json' );
</script>

因此，这个脚本将把密码字符串的散列发布到服务器。

有关其他哈希计算算法的进一步信息和支持，您可以访问:

http://code.google.com/p/crypto-js/

在选择库时，也要看它是否支持现代框架(如Bower)，是否通过jslint，是否支持JQuery插件模型或模块系统(如AMD/RequireJS)，以及是否正在积极开发中，是否有超过1个贡献者。有几个选项可以满足这些附加条件的一部分或全部:

CryptoJS: This is perhaps the most expansive library where each algorithm can be used separately without adding fat in to your JS code. Plus it as encoder/decoders for UTF8, UTF16 and Base64. I maintain github repository that is registered as Bower package plus instructions on how to use it with RequireJS. Spark MD5: This is based on JKM code that other answer mentions which is also the faster implementation. However in addition, Spark implementation adds AMD support, passes jslint plus has incremental mode. It doesn't have Base64 o/p but it does have raw o/p (i.e. array of 32-bit int insead of string). JQuery MD5 plugin: Very simple down to earth but doesn't seem to have raw mode. JavaScript-MD5: Not as fancy or fast as Spark but simpler.

来自CryptoJS的例子:

//just include md5.js from the CryptoJS rollups folder
var hash = CryptoJS.MD5("Message");
console.log(hash.toString()); 

在http://jsperf.com/md5-shootout/7上有上述库之间的性能比较。在我的机器上，当前的测试(不可否认是旧的)表明，如果您正在寻找速度，Spark MD5是您的最佳选择(普通JKM代码也是如此)。然而，如果你正在寻找更全面的库，那么CryptoJS是你最好的选择，尽管它比Spark MD5慢79%。然而，我想CryptoJS最终会达到同样的速度，因为它是一个更活跃的项目。

为什么不试试http://phpjs.org/functions/md5/?

不幸的是，任何模拟脚本的性能都是有限的，但是这可以呈现真正的md5散列。尽管我建议不要使用md5作为密码，因为它是一个快速呈现的散列。

我最喜欢的md5

这篇文章有42行长，横向可容纳120个字符，看起来不错。它快吗?好吧，它足够快了，它和所有其他JS实现差不多。但看着这些排列整齐的列，会有一种奇怪的满足感。不否认。

//  A formatted version of a popular md5 implementation.
//  Original copyright (c) Paul Johnston & Greg Holt.
//  The function itself is now 42 lines long.

function md5(inputString) {
    var hc="0123456789abcdef";
    function rh(n) {var j,s="";for(j=0;j<=3;j++) s+=hc.charAt((n>>(j*8+4))&0x0F)+hc.charAt((n>>(j*8))&0x0F);return s;}
    function ad(x,y) {var l=(x&0xFFFF)+(y&0xFFFF);var m=(x>>16)+(y>>16)+(l>>16);return (m<<16)|(l&0xFFFF);}
    function rl(n,c)            {return (n<<c)|(n>>>(32-c));}
    function cm(q,a,b,x,s,t)    {return ad(rl(ad(ad(a,q),ad(x,t)),s),b);}
    function ff(a,b,c,d,x,s,t)  {return cm((b&c)|((~b)&d),a,b,x,s,t);}
    function gg(a,b,c,d,x,s,t)  {return cm((b&d)|(c&(~d)),a,b,x,s,t);}
    function hh(a,b,c,d,x,s,t)  {return cm(b^c^d,a,b,x,s,t);}
    function ii(a,b,c,d,x,s,t)  {return cm(c^(b|(~d)),a,b,x,s,t);}
    function sb(x) {
        var i;var nblk=((x.length+8)>>6)+1;var blks=new Array(nblk*16);for(i=0;i<nblk*16;i++) blks[i]=0;
        for(i=0;i<x.length;i++) blks[i>>2]|=x.charCodeAt(i)<<((i%4)*8);
        blks[i>>2]|=0x80<<((i%4)*8);blks[nblk*16-2]=x.length*8;return blks;
    }
    var i,x=sb(inputString),a=1732584193,b=-271733879,c=-1732584194,d=271733878,olda,oldb,oldc,oldd;
    for(i=0;i<x.length;i+=16) {olda=a;oldb=b;oldc=c;oldd=d;
        a=ff(a,b,c,d,x[i+ 0], 7, -680876936);d=ff(d,a,b,c,x[i+ 1],12, -389564586);c=ff(c,d,a,b,x[i+ 2],17,  606105819);
        b=ff(b,c,d,a,x[i+ 3],22,-1044525330);a=ff(a,b,c,d,x[i+ 4], 7, -176418897);d=ff(d,a,b,c,x[i+ 5],12, 1200080426);
        c=ff(c,d,a,b,x[i+ 6],17,-1473231341);b=ff(b,c,d,a,x[i+ 7],22,  -45705983);a=ff(a,b,c,d,x[i+ 8], 7, 1770035416);
        d=ff(d,a,b,c,x[i+ 9],12,-1958414417);c=ff(c,d,a,b,x[i+10],17,     -42063);b=ff(b,c,d,a,x[i+11],22,-1990404162);
        a=ff(a,b,c,d,x[i+12], 7, 1804603682);d=ff(d,a,b,c,x[i+13],12,  -40341101);c=ff(c,d,a,b,x[i+14],17,-1502002290);
        b=ff(b,c,d,a,x[i+15],22, 1236535329);a=gg(a,b,c,d,x[i+ 1], 5, -165796510);d=gg(d,a,b,c,x[i+ 6], 9,-1069501632);
        c=gg(c,d,a,b,x[i+11],14,  643717713);b=gg(b,c,d,a,x[i+ 0],20, -373897302);a=gg(a,b,c,d,x[i+ 5], 5, -701558691);
        d=gg(d,a,b,c,x[i+10], 9,   38016083);c=gg(c,d,a,b,x[i+15],14, -660478335);b=gg(b,c,d,a,x[i+ 4],20, -405537848);
        a=gg(a,b,c,d,x[i+ 9], 5,  568446438);d=gg(d,a,b,c,x[i+14], 9,-1019803690);c=gg(c,d,a,b,x[i+ 3],14, -187363961);
        b=gg(b,c,d,a,x[i+ 8],20, 1163531501);a=gg(a,b,c,d,x[i+13], 5,-1444681467);d=gg(d,a,b,c,x[i+ 2], 9,  -51403784);
        c=gg(c,d,a,b,x[i+ 7],14, 1735328473);b=gg(b,c,d,a,x[i+12],20,-1926607734);a=hh(a,b,c,d,x[i+ 5], 4,    -378558);
        d=hh(d,a,b,c,x[i+ 8],11,-2022574463);c=hh(c,d,a,b,x[i+11],16, 1839030562);b=hh(b,c,d,a,x[i+14],23,  -35309556);
        a=hh(a,b,c,d,x[i+ 1], 4,-1530992060);d=hh(d,a,b,c,x[i+ 4],11, 1272893353);c=hh(c,d,a,b,x[i+ 7],16, -155497632);
        b=hh(b,c,d,a,x[i+10],23,-1094730640);a=hh(a,b,c,d,x[i+13], 4,  681279174);d=hh(d,a,b,c,x[i+ 0],11, -358537222);
        c=hh(c,d,a,b,x[i+ 3],16, -722521979);b=hh(b,c,d,a,x[i+ 6],23,   76029189);a=hh(a,b,c,d,x[i+ 9], 4, -640364487);
        d=hh(d,a,b,c,x[i+12],11, -421815835);c=hh(c,d,a,b,x[i+15],16,  530742520);b=hh(b,c,d,a,x[i+ 2],23, -995338651);
        a=ii(a,b,c,d,x[i+ 0], 6, -198630844);d=ii(d,a,b,c,x[i+ 7],10, 1126891415);c=ii(c,d,a,b,x[i+14],15,-1416354905);
        b=ii(b,c,d,a,x[i+ 5],21,  -57434055);a=ii(a,b,c,d,x[i+12], 6, 1700485571);d=ii(d,a,b,c,x[i+ 3],10,-1894986606);
        c=ii(c,d,a,b,x[i+10],15,   -1051523);b=ii(b,c,d,a,x[i+ 1],21,-2054922799);a=ii(a,b,c,d,x[i+ 8], 6, 1873313359);
        d=ii(d,a,b,c,x[i+15],10,  -30611744);c=ii(c,d,a,b,x[i+ 6],15,-1560198380);b=ii(b,c,d,a,x[i+13],21, 1309151649);
        a=ii(a,b,c,d,x[i+ 4], 6, -145523070);d=ii(d,a,b,c,x[i+11],10,-1120210379);c=ii(c,d,a,b,x[i+ 2],15,  718787259);
        b=ii(b,c,d,a,x[i+ 9],21, -343485551);a=ad(a,olda);b=ad(b,oldb);c=ad(c,oldc);d=ad(d,oldd);
    }
    return rh(a)+rh(b)+rh(c)+rh(d);
}

另一个完全无关的事实是:它有4000字节长。这似乎毫无意义，但知道就感觉很好。你看着它，你知道。你是秘密俱乐部的一员。生活将从此不同。相信我。

同时，感谢保罗·约翰斯顿和格雷格·霍尔特。 还有道格拉斯·亚当斯，所有的鱼。

Stackblitz试样

下面是@dkellner和@Eonasdan的md5实现的ES6版本:

const md5 = inputString => {
   const hc = '0123456789abcdef';
   const rh = n => {let j,s='';for(j=0;j<=3;j++) s+=hc.charAt((n>>(j*8+4))&0x0F)+hc.charAt((n>>(j*8))&0x0F);return s;}
   const ad = (x,y) => {let l=(x&0xFFFF)+(y&0xFFFF);let m=(x>>16)+(y>>16)+(l>>16);return (m<<16)|(l&0xFFFF);}
   const rl = (n,c) => (n<<c)|(n>>>(32-c));
   const cm = (q,a,b,x,s,t) => ad(rl(ad(ad(a,q),ad(x,t)),s),b);
   const ff = (a,b,c,d,x,s,t) => cm((b&c)|((~b)&d),a,b,x,s,t);
   const gg = (a,b,c,d,x,s,t) => cm((b&d)|(c&(~d)),a,b,x,s,t);
   const hh = (a,b,c,d,x,s,t) => cm(b^c^d,a,b,x,s,t);
   const ii = (a,b,c,d,x,s,t) => cm(c^(b|(~d)),a,b,x,s,t);
   const sb = x => {
      let i;const nblk=((x.length+8)>>6)+1;const blks=[];for(i=0;i<nblk*16;i++) { blks[i]=0 };
      for(i=0;i<x.length;i++) {blks[i>>2]|=x.charCodeAt(i)<<((i%4)*8);}
      blks[i>>2]|=0x80<<((i%4)*8);blks[nblk*16-2]=x.length*8;return blks;
   }
   let i,x=sb(inputString),a=1732584193,b=-271733879,c=-1732584194,d=271733878,olda,oldb,oldc,oldd;
   for(i=0;i<x.length;i+=16) {olda=a;oldb=b;oldc=c;oldd=d;
      a=ff(a,b,c,d,x[i+ 0], 7, -680876936);d=ff(d,a,b,c,x[i+ 1],12, -389564586);c=ff(c,d,a,b,x[i+ 2],17,  606105819);
      b=ff(b,c,d,a,x[i+ 3],22,-1044525330);a=ff(a,b,c,d,x[i+ 4], 7, -176418897);d=ff(d,a,b,c,x[i+ 5],12, 1200080426);
      c=ff(c,d,a,b,x[i+ 6],17,-1473231341);b=ff(b,c,d,a,x[i+ 7],22,  -45705983);a=ff(a,b,c,d,x[i+ 8], 7, 1770035416);
      d=ff(d,a,b,c,x[i+ 9],12,-1958414417);c=ff(c,d,a,b,x[i+10],17,     -42063);b=ff(b,c,d,a,x[i+11],22,-1990404162);
      a=ff(a,b,c,d,x[i+12], 7, 1804603682);d=ff(d,a,b,c,x[i+13],12,  -40341101);c=ff(c,d,a,b,x[i+14],17,-1502002290);
      b=ff(b,c,d,a,x[i+15],22, 1236535329);a=gg(a,b,c,d,x[i+ 1], 5, -165796510);d=gg(d,a,b,c,x[i+ 6], 9,-1069501632);
      c=gg(c,d,a,b,x[i+11],14,  643717713);b=gg(b,c,d,a,x[i+ 0],20, -373897302);a=gg(a,b,c,d,x[i+ 5], 5, -701558691);
      d=gg(d,a,b,c,x[i+10], 9,   38016083);c=gg(c,d,a,b,x[i+15],14, -660478335);b=gg(b,c,d,a,x[i+ 4],20, -405537848);
      a=gg(a,b,c,d,x[i+ 9], 5,  568446438);d=gg(d,a,b,c,x[i+14], 9,-1019803690);c=gg(c,d,a,b,x[i+ 3],14, -187363961);
      b=gg(b,c,d,a,x[i+ 8],20, 1163531501);a=gg(a,b,c,d,x[i+13], 5,-1444681467);d=gg(d,a,b,c,x[i+ 2], 9,  -51403784);
      c=gg(c,d,a,b,x[i+ 7],14, 1735328473);b=gg(b,c,d,a,x[i+12],20,-1926607734);a=hh(a,b,c,d,x[i+ 5], 4,    -378558);
      d=hh(d,a,b,c,x[i+ 8],11,-2022574463);c=hh(c,d,a,b,x[i+11],16, 1839030562);b=hh(b,c,d,a,x[i+14],23,  -35309556);
      a=hh(a,b,c,d,x[i+ 1], 4,-1530992060);d=hh(d,a,b,c,x[i+ 4],11, 1272893353);c=hh(c,d,a,b,x[i+ 7],16, -155497632);
      b=hh(b,c,d,a,x[i+10],23,-1094730640);a=hh(a,b,c,d,x[i+13], 4,  681279174);d=hh(d,a,b,c,x[i+ 0],11, -358537222);
      c=hh(c,d,a,b,x[i+ 3],16, -722521979);b=hh(b,c,d,a,x[i+ 6],23,   76029189);a=hh(a,b,c,d,x[i+ 9], 4, -640364487);
      d=hh(d,a,b,c,x[i+12],11, -421815835);c=hh(c,d,a,b,x[i+15],16,  530742520);b=hh(b,c,d,a,x[i+ 2],23, -995338651);
      a=ii(a,b,c,d,x[i+ 0], 6, -198630844);d=ii(d,a,b,c,x[i+ 7],10, 1126891415);c=ii(c,d,a,b,x[i+14],15,-1416354905);
      b=ii(b,c,d,a,x[i+ 5],21,  -57434055);a=ii(a,b,c,d,x[i+12], 6, 1700485571);d=ii(d,a,b,c,x[i+ 3],10,-1894986606);
      c=ii(c,d,a,b,x[i+10],15,   -1051523);b=ii(b,c,d,a,x[i+ 1],21,-2054922799);a=ii(a,b,c,d,x[i+ 8], 6, 1873313359);
      d=ii(d,a,b,c,x[i+15],10,  -30611744);c=ii(c,d,a,b,x[i+ 6],15,-1560198380);b=ii(b,c,d,a,x[i+13],21, 1309151649);
      a=ii(a,b,c,d,x[i+ 4], 6, -145523070);d=ii(d,a,b,c,x[i+11],10,-1120210379);c=ii(c,d,a,b,x[i+ 2],15,  718787259);
      b=ii(b,c,d,a,x[i+ 9],21, -343485551);a=ad(a,olda);b=ad(b,oldb);c=ad(c,oldc);d=ad(d,oldd);
   }
   return rh(a)+rh(b)+rh(c)+rh(d);
}

我听说Joseph的Myers实现非常快。此外，他还有一篇关于Javascript优化的长篇文章，描述了他在编写实现时学到的东西。对于任何对性能javascript感兴趣的人来说，这是一本很好的读物。

http://www.webreference.com/programming/javascript/jkm3/

他的MD5实现可以在这里找到