JSFiddle - React, Tailwind, and code Playground
JavaScript
var data = {"Top":{"person":{"A":"a","B":"b"}}};
if(data.Top.person instanceof Array)
alert(data.Top.person.length);
else
alert("I AM OBJECT");
if(Object.prototype.toString.call(data.Top.person) === '[object Array]')
alert(data.Top.person.length);
else
alert("I AM OBJECT");