Here is one example:
eval(function(p,a,c,k,e,d){e=function(c){return(c<a?'':e(parseInt(c/a)))+((c=c%a)>35?String.fromCharCode(c+29):c.toString(36))};if(!''.replace(/^/,String)){while(c--){d[e(c)]=k[c]||e(c)}k=[function(e){return d[e]}];e=function(){return'\\w+'};c=1};while(c--){if(k[c]){p=p.replace(new RegExp('\\b'+e(c)+'\\b','g'),k[c])}}return p}('4.h={H:9(d){T 7.F(9(){g 1=7;1.3={8:4(d.8,7),i:4(d.i,7),m:4.z.J(7),5:d.5,t:d.t,j:d.j,K:d.K,b:d.b,A:d.A};4.h.s(1,0);4(S).v(\'W\',9(){1.3.m=4.z.J(1);4.h.s(1,0);4.h.E(1)});4.h.E(1);1.3.8.v(\'O\',9(){4(1.3.t,7).l(0).a.I=\'P\'}).v(\'R\',9(){4(1.3.t,7).l(0).a.I=\'11\'});4(Z).v(\'10\',9(e){g p=4.z.Y(e);g c=0;k(1.3.b&&1.3.b==\'L\')g r=p.x-1.3.m.x-(1.w-1.3.5*1.3.8.n())/2-1.3.5/2;u k(1.3.b&&1.3.b==\'N\')g r=p.x-1.3.m.x-1.w+1.3.5*1.3.8.n();u g r=p.x-1.3.m.x;g M=B.G(p.y-1.3.m.y-1.X/2,2);1.3.8.F(9(q){6=B.Q(B.G(r-q*1.3.5,2)+M);6-=1.3.5/2;6=6<0?0:6;6=6>1.3.j?1.3.j:6;6=1.3.j-6;C=1.3.A*6/1.3.j;7.a.D=1.3.5+C+\'f\';7.a.o=1.3.5*q+c+\'f\';c+=C});4.h.s(1,c)})})},s:9(1,c){k(1.3.b)k(1.3.b==\'L\')1.3.i.l(0).a.o=(1.w-1.3.5*1.3.8.n())/2-c/2+\'f\';u k(1.3.b==\'o\')1.3.i.l(0).a.o=-c/1.3.8.n()+\'f\';u k(1.3.b==\'N\')1.3.i.l(0).a.o=(1.w-1.3.5*1.3.8.n())-c/2+\'f\';1.3.i.l(0).a.D=1.3.5*1.3.8.n()+c+\'f\'},E:9(1){1.3.8.F(9(q){7.a.D=1.3.5+\'f\';7.a.o=1.3.5*q+\'f\'})}};4.V.U=4.h.H;',62,64,'|el||fisheyeCfg|jQuery|itemWidth|distance|this|items|function|style|halign|toAdd|options||px|var|iFisheye|container|proximity|if|get|pos|size|left|pointer|nr|posx|positionContainer|itemsText|else|bind|offsetWidth|||iUtil|maxWidth|Math|extraWidth|width|positionItems|each|pow|build|display|getPosition|valign|center|posy|right|mouseover|block|sqrt|mouseout|window|return|Fisheye|fn|resize|offsetHeight|getPointer|document|mousemove|none'.split('|'),0,{}))
Obviously, this code is intentionally written to confuse other people. How can I understand it and rewrite it in simple code?
Is there some tool for this job? This is very common in HTML.
This is not "encrypted", it is just obfuscated.
Yes, there are tools available to help, but it isn't a perfect process. All of the original variable names and comments and what not are gone, so a tool can't really add that stuff back in. You have to figure out the details yourself, but a tool can make it easier.