get-value

What is get-value?

The get-value npm package is used for safely retrieving nested values from an object or array. It is useful when dealing with deeply nested structures where checking for the existence of each level can be cumbersome. It allows for specifying paths to the desired value using a string or an array of keys/indices.

What are get-value's main functionalities?

Get nested values

Retrieve a nested value from an object using a string path.

const get = require('get-value');
const obj = { a: { b: { c: 'd' } } };
console.log(get(obj, 'a.b.c')); // 'd'

Use array paths

Retrieve a nested value using an array of keys as the path.

const get = require('get-value');
const obj = { a: { b: { c: 'd' } } };
console.log(get(obj, ['a', 'b', 'c'])); // 'd'

Specify default values

Provide a default value to return if the full path does not exist.

const get = require('get-value');
const obj = { a: { b: { c: 'd' } } };
console.log(get(obj, 'a.b.e', { default: 'default value' })); // 'default value'

Split string paths

Retrieve values from keys that include a dot or other special characters by specifying a custom separator.

const get = require('get-value');
const obj = { 'a.b': { c: 'd' } };
console.log(get(obj, 'a\.b.c', { separator: '\.' })); // 'd'

Other packages similar to get-value

lodash.get

lodash.get is a method from the Lodash library that provides similar functionality to get-value. It allows for retrieving nested values with a default option. Lodash is a larger utility library, so lodash.get is part of a broader suite of tools.

dot-prop

dot-prop is another package that allows for getting and setting nested properties. Unlike get-value, dot-prop also supports setting values. It uses a dot notation string as the path.

deep-get-set

deep-get-set is a package that not only gets but also sets deep values. It is less popular than get-value and does not have as many configuration options.

README

get-value

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 :heart: and support.

Table of Contents

Details

• Install
• Usage
  • Supports keys with dots
  • Supports arrays
  • Supports functions
  • Supports passing object path as an array
• Options
  • options.default
  • options.isValid
  • options.split
  • options.separator
  • options.join
  • options.joinChar
• Benchmarks
  • Running the benchmarks
• Release history
  • v3.0.0
• About

Install

Install with npm:

$ npm install --save get-value

Usage

See the unit tests for many more examples.

const get = require('foo');
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')); 
//=> 'f'

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:

• has-any-deep: Return true if key exists deeply on the given object. | homepage
• has-any: Returns true if an object has any of the specified keys. | homepage
• has-value: Returns true if a value exists, false if empty. Works with deeply nested values using… more | homepage
• set-value: Create nested values and any intermediaries using dot notation ('a.b.c') paths. | homepage
• unset-value: Delete nested properties from an object using dot notation. | homepage

Contributors

Commits	Contributor
81	jonschlinkert
2	ianwalter
1	doowb

Author

Jon Schlinkert

• LinkedIn Profile
• GitHub Profile
• Twitter Profile

License

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

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This file was generated by verb-generate-readme, v0.6.0, on March 07, 2018.