Get Gravatar Using Only Javascript

Get Gravatar Using Only Javascript
Get Gravatar Using Only Javascript

Gravatar (globally recognized avatar) is an image that follows you from site to site appearing beside your name when you do things like comment or post on a blog. In a previous post, I showed you how to get gravatar in WordPress, in this post, we’ll see how to get gravatar using only Javascript.

First, let’s look at the URL of a gravatar image, it looks like:

http://www.gravatar.com/avatar/3b3be63a4c2a439b013787725dfce802.jpg?s=80

There’re 3 parts in the gravatar’s URL:

  • the URL base: that is http://www.gravatar.com/avatar/
  • the email hash: is the hexadecimal MD5 hash of the requested user’s lowercased email address with all whitespace trimmed, for example the fictitious “[email protected]” would have a hash of “3b3be63a4c2a439b013787725dfce802”. The image extension (.jpg) is optional.
  • the size: you can specify a “size” or “s” parameter to the URL between 1 and 512 (pixels.) to specify gravatar’s size. In the example above, we use 80×80 image size. This parameter is optional.

In Javascript, to get gravatar, we must implement a function to generate MD5 hash from an email address. We’ll use the MD5 function from WebToolkit.

The final code to get gravatar will be (the MD5 function has been packed by YUI Compressor):

function get_gravatar(email, size) {

    // MD5 (Message-Digest Algorithm) by WebToolkit
    // 

    var MD5=function(s){function L(k,d){return(k<<d)|(k>>>(32-d))}function K(G,k){var I,d,F,H,x;F=(G&2147483648);H=(k&2147483648);I=(G&1073741824);d=(k&1073741824);x=(G&1073741823)+(k&1073741823);if(I&d){return(x^2147483648^F^H)}if(I|d){if(x&1073741824){return(x^3221225472^F^H)}else{return(x^1073741824^F^H)}}else{return(x^F^H)}}function r(d,F,k){return(d&F)|((~d)&k)}function q(d,F,k){return(d&k)|(F&(~k))}function p(d,F,k){return(d^F^k)}function n(d,F,k){return(F^(d|(~k)))}function u(G,F,aa,Z,k,H,I){G=K(G,K(K(r(F,aa,Z),k),I));return K(L(G,H),F)}function f(G,F,aa,Z,k,H,I){G=K(G,K(K(q(F,aa,Z),k),I));return K(L(G,H),F)}function D(G,F,aa,Z,k,H,I){G=K(G,K(K(p(F,aa,Z),k),I));return K(L(G,H),F)}function t(G,F,aa,Z,k,H,I){G=K(G,K(K(n(F,aa,Z),k),I));return K(L(G,H),F)}function e(G){var Z;var F=G.length;var x=F+8;var k=(x-(x%64))/64;var I=(k+1)*16;var aa=Array(I-1);var d=0;var H=0;while(H<F){Z=(H-(H%4))/4;d=(H%4)*8;aa[Z]=(aa[Z]|(G.charCodeAt(H)<<d));H++}Z=(H-(H%4))/4;d=(H%4)*8;aa[Z]=aa[Z]|(128<<d);aa[I-2]=F<<3;aa[I-1]=F>>>29;return aa}function B(x){var k="",F="",G,d;for(d=0;d<=3;d++){G=(x>>>(d*8))&255;F="0"+G.toString(16);k=k+F.substr(F.length-2,2)}return k}function J(k){k=k.replace(/rn/g,"n");var d="";for(var F=0;F<k.length;F++){var x=k.charCodeAt(F);if(x<128){d+=String.fromCharCode(x)}else{if((x>127)&&(x<2048)){d+=String.fromCharCode((x>>6)|192);d+=String.fromCharCode((x&63)|128)}else{d+=String.fromCharCode((x>>12)|224);d+=String.fromCharCode(((x>>6)&63)|128);d+=String.fromCharCode((x&63)|128)}}}return d}var C=Array();var P,h,E,v,g,Y,X,W,V;var S=7,Q=12,N=17,M=22;var A=5,z=9,y=14,w=20;var o=4,m=11,l=16,j=23;var U=6,T=10,R=15,O=21;s=J(s);C=e(s);Y=1732584193;X=4023233417;W=2562383102;V=271733878;for(P=0;P<C.length;P+=16){h=Y;E=X;v=W;g=V;Y=u(Y,X,W,V,C[P+0],S,3614090360);V=u(V,Y,X,W,C[P+1],Q,3905402710);W=u(W,V,Y,X,C[P+2],N,606105819);X=u(X,W,V,Y,C[P+3],M,3250441966);Y=u(Y,X,W,V,C[P+4],S,4118548399);V=u(V,Y,X,W,C[P+5],Q,1200080426);W=u(W,V,Y,X,C[P+6],N,2821735955);X=u(X,W,V,Y,C[P+7],M,4249261313);Y=u(Y,X,W,V,C[P+8],S,1770035416);V=u(V,Y,X,W,C[P+9],Q,2336552879);W=u(W,V,Y,X,C[P+10],N,4294925233);X=u(X,W,V,Y,C[P+11],M,2304563134);Y=u(Y,X,W,V,C[P+12],S,1804603682);V=u(V,Y,X,W,C[P+13],Q,4254626195);W=u(W,V,Y,X,C[P+14],N,2792965006);X=u(X,W,V,Y,C[P+15],M,1236535329);Y=f(Y,X,W,V,C[P+1],A,4129170786);V=f(V,Y,X,W,C[P+6],z,3225465664);W=f(W,V,Y,X,C[P+11],y,643717713);X=f(X,W,V,Y,C[P+0],w,3921069994);Y=f(Y,X,W,V,C[P+5],A,3593408605);V=f(V,Y,X,W,C[P+10],z,38016083);W=f(W,V,Y,X,C[P+15],y,3634488961);X=f(X,W,V,Y,C[P+4],w,3889429448);Y=f(Y,X,W,V,C[P+9],A,568446438);V=f(V,Y,X,W,C[P+14],z,3275163606);W=f(W,V,Y,X,C[P+3],y,4107603335);X=f(X,W,V,Y,C[P+8],w,1163531501);Y=f(Y,X,W,V,C[P+13],A,2850285829);V=f(V,Y,X,W,C[P+2],z,4243563512);W=f(W,V,Y,X,C[P+7],y,1735328473);X=f(X,W,V,Y,C[P+12],w,2368359562);Y=D(Y,X,W,V,C[P+5],o,4294588738);V=D(V,Y,X,W,C[P+8],m,2272392833);W=D(W,V,Y,X,C[P+11],l,1839030562);X=D(X,W,V,Y,C[P+14],j,4259657740);Y=D(Y,X,W,V,C[P+1],o,2763975236);V=D(V,Y,X,W,C[P+4],m,1272893353);W=D(W,V,Y,X,C[P+7],l,4139469664);X=D(X,W,V,Y,C[P+10],j,3200236656);Y=D(Y,X,W,V,C[P+13],o,681279174);V=D(V,Y,X,W,C[P+0],m,3936430074);W=D(W,V,Y,X,C[P+3],l,3572445317);X=D(X,W,V,Y,C[P+6],j,76029189);Y=D(Y,X,W,V,C[P+9],o,3654602809);V=D(V,Y,X,W,C[P+12],m,3873151461);W=D(W,V,Y,X,C[P+15],l,530742520);X=D(X,W,V,Y,C[P+2],j,3299628645);Y=t(Y,X,W,V,C[P+0],U,4096336452);V=t(V,Y,X,W,C[P+7],T,1126891415);W=t(W,V,Y,X,C[P+14],R,2878612391);X=t(X,W,V,Y,C[P+5],O,4237533241);Y=t(Y,X,W,V,C[P+12],U,1700485571);V=t(V,Y,X,W,C[P+3],T,2399980690);W=t(W,V,Y,X,C[P+10],R,4293915773);X=t(X,W,V,Y,C[P+1],O,2240044497);Y=t(Y,X,W,V,C[P+8],U,1873313359);V=t(V,Y,X,W,C[P+15],T,4264355552);W=t(W,V,Y,X,C[P+6],R,2734768916);X=t(X,W,V,Y,C[P+13],O,1309151649);Y=t(Y,X,W,V,C[P+4],U,4149444226);V=t(V,Y,X,W,C[P+11],T,3174756917);W=t(W,V,Y,X,C[P+2],R,718787259);X=t(X,W,V,Y,C[P+9],O,3951481745);Y=K(Y,h);X=K(X,E);W=K(W,v);V=K(V,g)}var i=B(Y)+B(X)+B(W)+B(V);return i.toLowerCase()};

    var size = size || 80;

    return 'http://www.gravatar.com/avatar/' + MD5(email) + '.jpg?s=' + size;
}

To show a gravatar, use the following code:

document.write('<img src="' + get_gravatar('[email protected]', 50) + '" />');

Getting gravatar using Javascript is not often used. But in some cases, when you’re restricted by only client-side script (for example in design a HTML template) this post can help you.

4 thoughts on “Get Gravatar Using Only Javascript

  1. This isn’t quite right. Instead of MD5(email), it should be MD5(email.trim().toLowerCase()), as gravatar.com requires emails to be lowercased before MD5ing. Otherwise, if the user puts capitals int their email ([email protected]) their gravatar won’t show up! (Note that trim() doesn’t work on Internet Explorer <= 8; there are shims available.)

  2. This is a great article, I am going to use your code on one of my sites to display the avatar

Comments are closed.

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