How to access the first property of a Javascript object?

var obj = { first: 'someVal' };
obj[Object.keys(obj)[0]]; //returns 'someVal'

Object.values(obj)[0]; // returns 'someVal'

Using this you can access also other properties by indexes. Be aware tho! Object.keys or Object.values return order is not guaranteed as per ECMAScript however unofficially it is by all major browsers implementations, please read https://stackoverflow.com/a/23202095 for details on this.