如何度量将JSON字符串解析为Javascript对象的时间

I'm using AJAX query to get some long array from server side. The array is really big (let's say million elements), so even HTTP query takes a time, I see it in a console. But after the query is done, some time passes until I see an output which comes from a callback function of AJAX query.I'm using AJAX query to get some long array fro