@paxperscientiam/dlv.ts

Fork notice

This fork is a TypeScript implementation of dlv.

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?

Supports ES Modules, CommonJS and globals.

Installation

pnpm i @paxperscientiam/dlv.ts

or ...

npm i @paxperscientiam/dlv.ts

or ...

yarn add @paxperscientiam/dlv.ts

Usage

Available as dlvTs from dist/dlv.umd.js.

@paxperscientiam/dlv.ts uses a default export.

Code:

export default function dlv<T, K extends Extract<keyof T, string>>(obj: T,
                                                                   key: K|K[],
                                                                   def?: any,
                                                                   p: number = 0): any {
    const accessor = (key as string).split ? (key as string).split(".") : (key as string[])
    while (obj && p < accessor.length) {
        obj = obj[accessor[p++]]
    }
    return (obj === undefined || p < accessor.length) ? def : obj
}

delve(object, keypath, [default])

import delve from '@paxperscientiam/dlv.ts';

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.c.f') === undefined;

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

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

//Non-truthy defined values are still returned if they exist at the full keypath
delve(obj, 'a.b.c.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