In javascript, test for property deeply nested in object graph?

Question

I\'ve got a collection of disparate, complex JSON objects from a CouchDB database. Each contains many levels of nested properties--for example,

tps_report.p         


        

Answer 1

/**
 * units sold from each TPS report
 */

var units;

// the hard way
units = (report && report.personnel && report.personnel.info &&
        report.personnel.info.sales && report.personnel.info.sales.units &&
        report.personnel.info.sales.units.sold) || 0;

// the easy way
units = selectn('personnel.info.sales.units.sold', report) || 0;

// resulting action
if (units < 10) fireEmployee();

Shameless plug: I am the author of selectn. It is avaialble via npm install selectn or bower install selectn or component install wilmoore/selectn.

Check out the examples on the readme to find out why this is better than an isset clone. You can also use it as a filter predicate so you can scrub out nested objects that do not contain a particular deeply nested property.