{"head": [ 
{"text":"广州","id":"广州","pid":"广东省"}, 
{"text":"郑州","id":"郑州","pid":"河南省"}], 
}

var head_id = ""; 
var head_pid = ""; 
for (var i = 0; i < data.head.length; i++) { 
head_id += data.head[i].id + " "; //循环输出json数据 
head_pid += data.head[i].pid + " "; 
} 
$("#city").append("city:" + head_id); 
$("#city").append("province:" + head_pid);

for (var i = 0; i < data.head.length; i++) { 
if (data.head[i].pid == "河南省") { //有选择的输出json数据 
head_pid += data.head[i].pid; 
} 
}