developit / dlv

Safe deep property access in 120 bytes. x = dlv(obj, 'a.b.x')

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 120 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

dlv's Issues

types (TypeScript)

Hey! 👋

Thanks for this little gem 💎

I'm wondering are you open to committing TS type declaration to the repo? Or should I add them to DefinitelyTyped repo?

Argument 'p' is unnecessary in function signature

Version 10 of node.js has been released

Version 10 of Node.js (code name Dubnium) has been released! 🎊

To see what happens to your code in Node.js 10, Greenkeeper has created a branch with the following changes:

• Added the new Node.js version to your .travis.yml

If you’re interested in upgrading this repo to Node.js 10, you can open a PR with these changes. Please note that this issue is just intended as a friendly reminder and the PR as a possible starting point for getting your code running on Node.js 10.

More information on this issue

Greenkeeper has checked the engines key in any package.json file, the .nvmrc file, and the .travis.yml file, if present.

• engines was only updated if it defined a single version, not a range.
• .nvmrc was updated to Node.js 10
• .travis.yml was only changed if there was a root-level node_js that didn’t already include Node.js 10, such as node or lts/*. In this case, the new version was appended to the list. We didn’t touch job or matrix configurations because these tend to be quite specific and complex, and it’s difficult to infer what the intentions were.

For many simpler .travis.yml configurations, this PR should suffice as-is, but depending on what you’re doing it may require additional work or may not be applicable at all. We’re also aware that you may have good reasons to not update to Node.js 10, which is why this was sent as an issue and not a pull request. Feel free to delete it without comment, I’m a humble robot and won’t feel rejected 🤖

---

FAQ and help

There is a collection of frequently asked questions. If those don’t help, you can always ask the humans behind Greenkeeper.

---

Your Greenkeeper Bot 🌴

do you have the setter counterpart laying around?

Love this library, but in the market for a tiny setter too.

An in-range update of microbundle is breaking the build 🚨

Version 0.4.5 of microbundle was just published.

Branch	Build failing 🚨
Dependency	microbundle
Current Version	0.4.4
Type	devDependency

This version is covered by your current version range and after updating it in your project the build failed.

microbundle is a devDependency of this project. It might not break your production code or affect downstream projects, but probably breaks your build or test tools, which may prevent deploying or publishing.

Status Details

• ❌ continuous-integration/travis-ci/push The Travis CI build could not complete due to an error Details

---

Commits

The new version differs by 63 commits.

• 6a95870 0.4.5
• 41e0dc3 Fix mangle.json name caching (seemed to break in a recent rollup update)
• 42050bb Fix Rollup upgrade adding __esModule properties to exports.
• 0a6a791 Merge pull request #161 from philipp-spiess/patch-1
• 1ffccee Add react-recomponent to "Built with Microbundle"
• bf2d068 Updated rollup to 0.60.1, made code changes to support it (#151)
• 8286def Merge pull request #153 from mattdesl/fix/111
• fcbfa8f Merge pull request #149 from developit/greenkeeper/pretty-bytes-5.1.0
• d786f03 fix #111 and log errors during watch
• 8393af2 fix(package): update pretty-bytes to version 5.1.0
• 818a7d5 Revert "Update rollup to the latest version 🚀" (#148)
• c7fbe3e Merge pull request #145 from developit/greenkeeper/rollup-0.60.0
• 9d77676 fix(package): update rollup to version 0.60.0
• 4d5ff56 Turn off eslint rules inconsistent with prettier settings and run prettier through eslint (#136)
• 3afc4f4 Merge pull request #140 from developit/greenkeeper/rollup-0.59.3

There are 63 commits in total.

See the full diff

FAQ and help

There is a collection of frequently asked questions. If those don’t help, you can always ask the humans behind Greenkeeper.

---

Your Greenkeeper Bot 🌴

Missing copyright notice

The project is licensed under MIT, but lacks a copyright notice.

It does not support keys with dots

If you have an object like this:

const obj = {
  'hello.word': 'Hello Word'
};

You cannot access to the string with that package.

See https://github.com/sindresorhus/dot-prop

array item access?

lodash.get allows for something like this:

get(obj, 'foo[0]')

which would correspond to:

obj = {
  foo: [
    'x' // <-
  ],
}

Any chance this could be supported in dlv as well?

undefined key throws

From the readme:

//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';

Feature: Default when not found

I've found us doing this pattern a lot when using dlv:

let foo = dlv(bar, 'a.b.c');
if(typeof foo === 'undefined') foo = defaultFoo;

It might be useful to allow dlv to support a third argument that is a default return value if the key is not found

Shorter version

Smallest possible implementation: only 120 bytes.

There's possibly smaller version:

export dlv = (obj, key) => (key.split ? key.split('.') : key).reduce((a,b)=>b?a?.[b]:a,obj)

Default is working wrong for nested null value

import delve from 'dlv'

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

console.log(delve(obj, 'a.c', 'default')) // 1
console.log(delve(obj, 'a.c.f', 'default')) // default

console.log(delve(obj, 'a.d', 'default')) // default
console.log(delve(obj, 'a.d.f', 'default')) // default

console.log(delve(obj, 'a.e', 'default')) // null
console.log(delve(obj, 'a.e.f', 'default')) // null <- bug

The last one is nested key over null value, it doesn't exist but returns null instead of default value.

Default for undefined value

whops, a wrong one :)

130 bytes is smallest possible?

If you make a statement like that you can always count on a smart ass to respond

• p can be declared as default value
• split('.') can be written as split`.`
• length is used twice

How about something like:

export default dlv = (
    obj,
    key,
    def,
    p=0,
    k=key.split ? key.split`.` : key,
    l=k.length
) => {
           while (obj && p<l) obj = obj[k[p++]];
           return (obj===undefined || p<l) ? def : obj;   
}

... haven't tested it

Or to get rid of the return

export default dlv = (
    obj,
    key,
    def,
    p=0,
    k=key.split ? key.split`.` : key,
    l=k.length,
    o=(_=>{while (obj && p<l) obj = obj[k[p++]]})()
) => (obj===undefined || p<l) ? def : obj;

jscalpel A small feature library that makes it easier to manipulate objects

Hi @developit , I have developed a similar library before and provided more powerful features.
https://github.com/ihtml5/jscalpel Welcome attention