var ob = {};
$.each( input, function( key, value ) {
    var v = [];
    ob[key] = v.push(value);
      console.log( v );
      console.log( "obj: " + ob );
      console.log( key + ": " + value );
    });

First input- {A: "34",B: "2"}
Second input- {A: "21",B: "11"}

ob = {A: ["34","21"] ,B: ["2","11"]}