Create object of occurrences of numbers

JavaScript

var data = ['wa','a','e','d'];
var data2 = ['1','2','3','4'];
    o = {};
    var b = [];

for (i = 0; i < data.length; i++) {
    o[data[i]] = data2[i];
}
o['cc'] = 'cc';
b.push(o);
console.log(o);
alert(JSON.stringify(o));