.verb.md

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.

{%= include("./benchmark/stats.md") %}

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.