if "propertyName" in obj

by JakobJingleheimer

HTML

<div id="log"></div>

JavaScript

var foo = { "a": [0,1,2], "b": { "values": [3,4,5] } };

var log = function(data) {
    console.log('data\t',data);
    this.outputLog = document.getElementById("log");
    data = ( typeof data === 'object' )? JSON.stringify(data) : data;
    this.outputLog.innerHTML = data;
};
if ( "values" in foo.b ) log(foo.b.values);