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README.md

get-value NPM version NPM monthly downloads NPM total downloads Linux Build Status

Use property paths like 'a.b.c' to get a nested value from an object. Even works when keys have dots in them (no other dot-prop library can do this!).

Please consider following this project's author, Jon Schlinkert, and consider starring the project to show your ❤️ and support.

Table of Contents

Details

Install

Install with npm:

$ npm install --save get-value

Usage

See the unit tests for many more examples.

const get = require('get-value');
const obj = { a: { b: { c: { d: 'foo' } } } };

console.log(get(obj));            //=> { a: { b: { c: { d: 'foo' } } } };
console.log(get(obj, 'a'));       //=> { b: { c: { d: 'foo' } } }
console.log(get(obj, 'a.b'));     //=> { c: { d: 'foo' } }
console.log(get(obj, 'a.b.c'));   //=> { d: 'foo' }
console.log(get(obj, 'a.b.c.d')); //=> 'foo'

Supports keys with dots

Unlike other dot-prop libraries, get-value works when keys have dots in them:

console.log(get({ 'a.b': { c: 'd' } }, 'a.b.c'));
//=> 'd'

console.log(get({ 'a.b': { c: { 'd.e': 'f' } } }, 'a.b.c.d.e'));
//=> 'f'

Supports arrays

console.log(get({ a: { b: { c: { d: 'foo' } } }, e: [{ f: 'g' }, { f: 'h' }] }, 'e.1.f'));   
//=> 'h'

console.log(get({ a: { b: [{ c: 'd' }] } }, 'a.b.0.c')); 
//=> 'd'

console.log(get({ a: { b: [{ c: 'd' }, { e: 'f' }] } }, 'a.b.1.e'));
//=> 'f'

Supports functions

function foo() {}
foo.bar = { baz: 'qux' };

console.log(get(foo));            
//=> { [Function: foo] bar: { baz: 'qux' } }

console.log(get(foo, 'bar'));     
//=> { baz: 'qux' }

console.log(get(foo, 'bar.baz')); 
//=> qux

Supports passing object path as an array

Slighly improve performance by passing an array of strings to use as object path segments (this is also useful when you need to dynamically build up the path segments):

console.log(get({ a: { b: 'c' } }, ['a', 'b']));
//=> 'c'

Options

options.default

Type: any

Default: undefined

The default value to return when get-value cannot resolve a value from the given object.

const obj = { foo: { a: { b: { c: { d: 'e' } } } } };
console.log(get(obj, 'foo.a.b.c.d', { default: true }));  //=> 'e'
console.log(get(obj, 'foo.bar.baz', { default: true }));  //=> true
console.log(get(obj, 'foo.bar.baz', { default: false })); //=> false
console.log(get(obj, 'foo.bar.baz', { default: null }));  //=> null

// you can also pass the default value as the last argument
// (this is necessary if the default value is an object)
console.log(get(obj, 'foo.a.b.c.d', true));  //=> 'e'
console.log(get(obj, 'foo.bar.baz', true));  //=> true
console.log(get(obj, 'foo.bar.baz', false)); //=> false
console.log(get(obj, 'foo.bar.baz', null));  //=> null

options.isValid

Type: function

Default: true

If defined, this function is called on each resolved value. Useful if you want to do .hasOwnProperty or Object.prototype.propertyIsEnumerable.

const isEnumerable = Object.prototype.propertyIsEnumerable;
const options = {
  isValid: (key, obj) => isEnumerable.call(obj, key)
};

const obj = {};
Object.defineProperty(obj, 'foo', { value: 'bar', enumerable: false });

console.log(get(obj, 'foo', options));           //=> undefined
console.log(get({}, 'hasOwnProperty', options)); //=> undefined
console.log(get({}, 'constructor', options));    //=> undefined

// without "isValid" check
console.log(get(obj, 'foo', options));           //=> bar
console.log(get({}, 'hasOwnProperty', options)); //=> [Function: hasOwnProperty]
console.log(get({}, 'constructor', options));    //=> [Function: Object]

options.split

Type: function

Default: String.split()

Custom function to use for splitting the string into object path segments.

const obj = { 'a.b': { c: { d: 'e' } } };

// example of using a string to split the object path
const options = { split: path => path.split('/') };
console.log(get(obj, 'a.b/c/d', options)); //=> 'e'

// example of using a regex to split the object path
// (removing escaped dots is unnecessary, this is just an example)
const options = { split: path => path.split(/\\?\./) };
console.log(get(obj, 'a\\.b.c.d', options)); //=> 'e'

options.separator

Type: string|regex

Default: .

The separator to use for spliting the string (this is probably not needed when options.split is used).

const obj = { 'a.b': { c: { d: 'e' } } };

console.log(get(obj, 'a.b/c/d', { separator: '/' }));       
//=> 'e'

console.log(get(obj, 'a\\.b.c.d', { separator: /\\?\./ })); 
//=> 'e'

options.join

Type: function

Default: Array.join()

Customize how the object path is created when iterating over path segments.

const obj = { 'a/b': { c: { d: 'e' } } };
const options = {
  // when segs === ['a', 'b'] use a "/" to join, otherwise use a "."
  join: segs => segs.join(segs[0] === 'a' ? '/' : '.')
};

console.log(get(obj, 'a.b.c.d', options));
//=> 'e'

options.joinChar

Type: string

Default: .

The character to use when re-joining the string to check for keys with dots in them (this is probably not needed when options.join is used). This can be a different value than the separator, since the separator can be a string or regex.

const target = { 'a-b': { c: { d: 'e' } } };
const options = { joinChar: '-' };
console.log(get(target, 'a.b.c.d', options)); 
//=> 'e'

Benchmarks

(benchmarks were run on a MacBook Pro 2.5 GHz Intel Core i7, 16 GB 1600 MHz DDR3).

get-value is more reliable and has more features than dot-prop, without sacrificing performance.

# deep (175 bytes)
  dot-prop x 883,166 ops/sec ±0.93% (86 runs sampled)
  get-value x 1,448,928 ops/sec ±1.53% (87 runs sampled)
  getobject x 213,797 ops/sec ±0.85% (90 runs sampled)
  object-path x 184,347 ops/sec ±2.48% (85 runs sampled)

  fastest is get-value (by 339% avg)

# root (210 bytes)
  dot-prop x 3,905,828 ops/sec ±1.36% (87 runs sampled)
  get-value x 16,391,934 ops/sec ±1.43% (83 runs sampled)
  getobject x 1,200,021 ops/sec ±1.81% (88 runs sampled)
  object-path x 2,788,494 ops/sec ±1.81% (86 runs sampled)

  fastest is get-value (by 623% avg)

# shallow (84 bytes)
  dot-prop x 2,553,558 ops/sec ±0.89% (89 runs sampled)
  get-value x 3,070,159 ops/sec ±0.88% (90 runs sampled)
  getobject x 726,670 ops/sec ±0.81% (86 runs sampled)
  object-path x 922,351 ops/sec ±2.05% (86 runs sampled)

  fastest is get-value (by 219% avg)

Running the benchmarks

Clone this library into a local directory:

$ git clone https://github.com/jonschlinkert/get-value.git

Then install devDependencies and run benchmarks:

$ npm install && node benchmark

Release history

v3.0.0

  • Improved support for escaping. It's no longer necessary to use backslashes to escape keys.
  • Adds options.default for defining a default value to return when no value is resolved.
  • Adds options.isValid to allow the user to check the object after each iteration.
  • Adds options.separator for customizing character to split on.
  • Adds options.split for customizing how the object path is split.
  • Adds options.join for customizing how the object path is joined when iterating over path segments.
  • Adds options.joinChar for customizing the join character.

About

Contributing

Pull requests and stars are always welcome. For bugs and feature requests, please create an issue.

Running Tests

Running and reviewing unit tests is a great way to get familiarized with a library and its API. You can install dependencies and run tests with the following command:

$ npm install && npm test
Building docs

(This project's readme.md is generated by verb, please don't edit the readme directly. Any changes to the readme must be made in the .verb.md readme template.)

To generate the readme, run the following command:

$ npm install -g verbose/verb#dev verb-generate-readme && verb

Related projects

You might also be interested in these projects:

Contributors

Commits Contributor
87 jonschlinkert
2 ianwalter
1 doowb

Author

Jon Schlinkert

License

Copyright © 2018, Jon Schlinkert. Released under the MIT License.


This file was generated by verb-generate-readme, v0.8.0, on November 17, 2018.

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