JSFiddle - React, Tailwind, and code Playground
by Nick Craver
HTML
<link rel="stylesheet" href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8/themes/dot-luv/jquery-ui.css">
JavaScript
var json ={"A":"a","B":"b","x":"y","a":"b"}
var key = "A";
var value = json[key];
alert(value); //in the object
alert(json["NotThere"]); //not in the object