Minified Sha256 implementation in javascript from: http://www.movable-type.co.uk/scripts/sha256.html

example.txt

Taken from: http://www.movable-type.co.uk/scripts/sha256.html
Put into: http://closure-compiler.appspot.com/home

exports:

/**
 * Generates SHA-256 hash of string
 *
 * @param {String} msg                String to be hashed
 * @param {Boolean} [utf8encode=true] Encode msg as UTF-8 before generating hash
 * @returns {String}                  Hash of msg as hex character string
 */
window.Sha256.hash = function(){...}

Untested usage:
console.log(window.Sha256.hash("The cat is not a cat"));

sha256.js

var c={};
c.hash=function(a,f){("undefined"==typeof f||f)&&(a=t(a));for(var h=[1116352408,1899447441,3049323471,3921009573,961987163,1508970993,2453635748,2870763221,3624381080,310598401,607225278,1426881987,1925078388,2162078206,2614888103,3248222580,3835390401,4022224774,264347078,604807628,770255983,1249150122,1555081692,1996064986,2554220882,2821834349,2952996808,3210313671,3336571891,3584528711,113926993,338241895,666307205,773529912,1294757372,1396182291,1695183700,1986661051,2177026350,2456956037,2730485921,
2820302411,3259730800,3345764771,3516065817,3600352804,4094571909,275423344,430227734,506948616,659060556,883997877,958139571,1322822218,1537002063,1747873779,1955562222,2024104815,2227730452,2361852424,2428436474,2756734187,3204031479,3329325298],b=[1779033703,3144134277,1013904242,2773480762,1359893119,2600822924,528734635,1541459225],a=a+String.fromCharCode(128),i=Math.ceil((a.length/4+2)/16),j=Array(i),g=0;g<i;g++){j[g]=Array(16);for(var e=0;16>e;e++)j[g][e]=a.charCodeAt(64*g+4*e)<<24|a.charCodeAt(64*
g+4*e+1)<<16|a.charCodeAt(64*g+4*e+2)<<8|a.charCodeAt(64*g+4*e+3)}j[i-1][14]=8*(a.length-1)/Math.pow(2,32);j[i-1][14]=Math.floor(j[i-1][14]);j[i-1][15]=8*(a.length-1)&4294967295;for(var e=Array(64),k,m,n,q,l,o,p,r,g=0;g<i;g++){for(var d=0;16>d;d++)e[d]=j[g][d];for(d=16;64>d;d++)e[d]=c.h(e[d-2])+e[d-7]+c.g(e[d-15])+e[d-16]&4294967295;k=b[0];m=b[1];n=b[2];q=b[3];l=b[4];o=b[5];p=b[6];r=b[7];for(d=0;64>d;d++){var s=r+c.f(l)+c.c(l,o,p)+h[d]+e[d],u=c.e(k)+c.d(k,m,n);r=p;p=o;o=l;l=q+s&4294967295;q=n;n=m;
m=k;k=s+u&4294967295}b[0]=b[0]+k&4294967295;b[1]=b[1]+m&4294967295;b[2]=b[2]+n&4294967295;b[3]=b[3]+q&4294967295;b[4]=b[4]+l&4294967295;b[5]=b[5]+o&4294967295;b[6]=b[6]+p&4294967295;b[7]=b[7]+r&4294967295}return c.b(b[0])+c.b(b[1])+c.b(b[2])+c.b(b[3])+c.b(b[4])+c.b(b[5])+c.b(b[6])+c.b(b[7])};c.a=function(a,f){return f>>>a|f<<32-a};c.e=function(a){return c.a(2,a)^c.a(13,a)^c.a(22,a)};c.f=function(a){return c.a(6,a)^c.a(11,a)^c.a(25,a)};c.g=function(a){return c.a(7,a)^c.a(18,a)^a>>>3};
c.h=function(a){return c.a(17,a)^c.a(19,a)^a>>>10};c.c=function(a,f,h){return a&f^~a&h};c.d=function(a,f,h){return a&f^a&h^f&h};c.b=function(a){for(var f="",h,b=7;0<=b;b--)h=a>>>4*b&15,f+=h.toString(16);return f};function t(a){a=a.replace(/[\u0080-\u07ff]/g,function(a){a=a.charCodeAt(0);return String.fromCharCode(192|a>>6,128|a&63)});return a=a.replace(/[\u0800-\uffff]/g,function(a){a=a.charCodeAt(0);return String.fromCharCode(224|a>>12,128|a>>6&63,128|a&63)})}window.Sha256=c;