UOP

UOP stands for Undefined Object Properties and is a tiny library which works on Node and browser which simply checks for undefined properties or nested properties on objects. We all have seen even in highly-skilled developers groups checking for undefined properties like:

if (
  obj &&
  obj.nested &&
  obj.nested.datetime &&
  obj.nested.datetime.time &&
  obj.nested.datetime.time.hours &&
  obj.nested.datetime.time.hours.stringFormat
) return true;

This is awful and we all should avoid it. It is frequently common also the other way, not checking all of the nested properties on an object which produce TypeError and crash your application. With UOP we can do:

if (uop(obj, 'nested.datetime.time.hours.stringFormat')) return true

And it will just return the value of the property if all nested properties are not undefined on the object or null if any of them are. If so, you should be responsible for finding out which of the properties is causing a problem, because actually UOP does not provide this functionality.

Getting started

• Using the library

npm i --save @jorchgg/uop

const uop = require('@jorchgg/uop');
const assert = require('assert');

const objWithNestedProperties = {
  'nested': {
    'datetime': {
      'time': {
        'hours': {
          'stringFormat': 'Sun, 02 Jun 2019 17:40:59 GMT',
        },
      },
    }, 
  },
};

assert.strictEqual(uop(objWithNestedProperties, 'nested.datetime.time.hours.stringFormat'), 'Sun, 02 Jun 2019 17:40:59 GMT');
assert.strictEqual(uop(objWithNestedProperties, 'nested.inexistentProp.time.hours.stringFormat'), null);

// It also supports arrays
const objWithNestedArray = {
  'nested': {
    'hours': [
      {
        'first': 9,
      },
      {
        'second': 10
      },
    ],
  },
};

assert.strictEqual(uop(objWithNestedArray, 'nested.hours[0].first'), 9);
assert.strictEqual(uop(objWithNestedArray, 'nested.hours[1].second'), 10);
assert.strictEqual(uop(objWithNestedArray, 'nested.hours[2].first'), null);

• Running the tests npm test builds the library, then tests it.

License

MIT.