dlv

What is dlv?

The dlv npm package is a safe deep property access utility. It allows you to access deeply nested properties within an object without the risk of throwing an error if a part of the path does not exist. It's particularly useful when dealing with complex data structures where some properties may be undefined or null.

What are dlv's main functionalities?

Safe property access

Access a deeply nested property without throwing if the path does not exist.

const dlv = require('dlv');
const obj = { a: { b: { c: 1 } } };
const value = dlv(obj, 'a.b.c'); // 1

Default value

Provide a default value if the deep property is undefined.

const dlv = require('dlv');
const obj = { a: { b: { } } };
const value = dlv(obj, 'a.b.c', 'default'); // 'default'

Access array indexes

Access an array index within a deeply nested structure.

const dlv = require('dlv');
const obj = { a: { b: [1, 2, 3] } };
const value = dlv(obj, ['a', 'b', 0]); // 1

Other packages similar to dlv

lodash.get

Lodash's get function is similar to dlv in that it allows for safe access to nested object properties. It is part of the larger Lodash library which offers a wide range of utilities for working with arrays, numbers, objects, strings, etc. Compared to dlv, lodash.get is part of a larger utility library, which might be preferable for some projects that can make use of other Lodash functions.

idx

The idx library provides a utility to safely access deeply nested properties in JavaScript. It uses a callback pattern and is built with TypeScript support. idx is similar to dlv but uses a different syntax and can be more verbose. It also supports TypeScript out of the box, which can be a deciding factor for projects using TypeScript.

README

dlv(obj, keypath)

Safely get a dot-notated path within a nested object, with ability to return a default if the full key path does not exist or the value is undefined

Why?

Smallest possible implementation: only 130 bytes.

You could write this yourself, but then you'd have to write tests.

Supports ES Modules, CommonJS and globals.

Installation

npm install --save dlv

Usage

delve(object, keypath, [default])

import delve from 'dlv';

let obj = {
	a: {
		b: {
			c: 1,
			d: undefined,
			e: null
		}
	}
};

//use string dot notation for keys
delve(obj, 'a.b.c') === 1;

//or use an array key
delve(obj, ['a', 'b', 'c']) === 1;

delve(obj, 'a.b') === obj.a.b;

//returns undefined if the full key path does not exist and no default is specified
delve(obj, 'a.b.f') === undefined;

//optional third parameter for default if the full key in path is missing
delve(obj, 'a.b.f', 'foo') === 'foo';

//or if the key exists but the value is undefined
delve(obj, 'a.b.d', 'foo') === 'foo';

//Non-truthy defined values are still returned if they exist at the full keypath
delve(obj, 'a.b.e', 'foo') === null;

//undefined obj or key returns undefined, unless a default is supplied
delve(undefined, 'a.b.c') === undefined;
delve(undefined, 'a.b.c', 'foo') === 'foo';
delve(obj, undefined, 'foo') === 'foo';

Setter Counterparts

• dset by @lukeed is the spiritual "set" counterpart of dlv and very fast.
• bury by @kalmbach does the opposite of dlv and is implemented in a very similar manner.

License

MIT