var str='offer?';

​

var names = ['channelId', 'channelId', 'offerType', 'offerType', 'Language'];

​

var values =[647, 763, 'international', 'programming', 'English'];

​

var last = '';

​

for (var i=0; i<names.length; i++) {

  var name = names[i];

  if (last === name) {

    str+=','+values[i];

  } else {

      if (i !== 0) {

        str+='&';

      }

    str+=name+'='+values[i];

  }

  last = name;

​

}

​

console.log(str);