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A tiny (196B) utility for safely writing deep Object values~!

For accessing deep object properties, please see dlv.

Using GraphQL? You may want dset/merge – see Merging for more info.

Install

$ npm install --save dset

Modes

There are two "versions" of dset available:

dset

Size (gzip): 196 bytes
Availability: CommonJS, ES Module, UMD

import { dset } from 'dset';

dset/merge

Size (gzip): 289 bytes
Availability: CommonJS, ES Module, UMD

import { dset } from 'dset/merge';

Usage

import { dset } from 'dset';

let foo = { abc: 123 };
dset(foo, 'foo.bar', 'hello');
// or: dset(foo, ['foo', 'bar'], 'hello');
console.log(foo);
//=> {
//=>   abc: 123,
//=>   foo: { bar: 'hello' },
//=> }

dset(foo, 'abc.hello', 'world');
// or: dset(foo, ['abc', 'hello'], 'world');
console.log(foo);
//=> {
//=>   abc: { hello: 'world' },
//=>   foo: { bar: 'hello' },
//=> }

let bar = { a: { x: 7 }, b:[1, 2, 3] };
dset(bar, 'bar.1', 999);
// or: dset(bar, ['bar', 1], 999);
// or: dset(bar, ['bar', '1'], 999);
console.log(bar);
//=> {
//=>   a: { x: 7 },
//=>   bar: [1, 999, 3],
//=> }

dset(bar, 'a.y.0', 8);
// or: dset(bar, ['a', 'y', 0], 8);
// or: dset(bar, ['a', 'y', '0'], 8);
console.log(bar);
//=> {
//=>   a: {
//=>     x: 7,
//=>     y: [8],
//=>   },
//=>   bar: [1, 999, 3],
//=> }

let baz = {};
dset(baz, 'a.0.b.0', 1);
dset(baz, 'a.0.b.1', 2);
console.log(baz);
//=> {
//=>   a: [{ b: [1, 2] }]
//=> }

Merging

The main/default dset module forcibly writes values at the assigned key-path. However, in some cases, you may prefer to merge values at the key-path. For example, when using GraphQL's @stream and @defer directives, you will need to merge the response chunks into a single object/list. This is why dset/merge exists~!

Below is a quick illustration of the difference between dset and dset/merge:

let input = {
  hello: {
    abc: 123
  }
};

dset(input, 'hello', { world: 123 });
console.log(input);

// via `dset`
//=> {
//=>   hello: {
//=>     world: 123
//=>   }
//=> }

// via `dset/merge`
//=> {
//=>   hello: {
//=>     abc: 123,
//=>     world: 123
//=>   }
//=> }

Immutability

As shown in the examples above, all dset interactions mutate the source object.

If you need immutable writes, please visit clean-set (182B).
Alternatively, you may pair dset with klona, a 366B utility to clone your source(s). Here's an example pairing:

import { dset } from 'dset';
import { klona } from 'klona';

export function deepset(obj, path, val) {
  let copy = klona(obj);
  dset(copy, path, val);
  return copy;
}

API

dset(obj, path, val)

Returns: void

obj

Type: Object

The Object to traverse & mutate with a value.

path

Type: String or Array

The key path that should receive the value. May be in x.y.z or ['x', 'y', 'z'] formats.

Note: Please be aware that only the last key actually receives the value!

Important: New Objects are created at each segment if there is not an existing structure.
However, when integers are encounted, Arrays are created instead!

value

Type: Any

The value that you want to set. Can be of any type!

Benchmarks

For benchmarks and full results, check out the bench directory!

# Node 10.13.0

Validation:
  ✔ set-value
  ✔ lodash/set
  ✔ dset

Benchmark:
  set-value    x 1,701,821 ops/sec ±1.81% (93 runs sampled)
  lodash/set   x   975,530 ops/sec ±0.96% (91 runs sampled)
  dset         x 1,797,922 ops/sec ±0.32% (94 runs sampled)

Related

  • dlv - safely read from deep properties in 120 bytes
  • dequal - safely check for deep equality in 247 bytes
  • klona - quickly "deep clone" data in 200 to 330 bytes
  • clean-set - fast, immutable version of dset in 182 bytes

License

MIT © Luke Edwards