Jquery create variable equal ajax data, then work with jquery Autocomplete

Question

I need to use the variable name equal the json post comeback data, then use jquery autocomplete, Can i do like that ? and why that error

var name=[];

$.post(url,{name:'name'},function(data){
 getdata(data);
}

function getdata(data){
  name=data;
 }

$('#textbox').autocomplete({
 source:name
})