function deepCopy(target,answer) {
var answer = answer ?answer :{};
for (var a in target) {
if(typeof target[a] === "object") {
if(target[a] === null) {
answer[a] = null;
}
else {
answer[a] = target[a].constructor ===Array ? [] : {};//后面的：{}其实可以不需要，只是为了好看，有点冗余的味道
deepCopy(target[a],answer[a]);
}
}
else {
answer[a] = target[a];
}
}
return answer;
}
