get-lookup

JS helper for object deeply nested properties lookup. Much like lodash.get, but with some additional useful features.

Installation

npm install --save get-lookup

Usage

Considering we have following object:

const obj = {
  foo: {
    bars: [{
      bak: 1,
      baz: 1
    }, {
      bak: 1,
      baz: 2
    }, {
      bak: 2,
      baz: 3
    }]
  }
};

Basic Usage

Path segments are delimitered by '.'.

import get from 'get-lookup';
 
get(obj, 'foo.bars.1.baz'); // => 2

Property Lookup Keys

Probably the most useful feature of get-lookup is ability to address objects inside of arrays by their properties via lookup keys. In the example bellow we use lookup key {bak:1}, which resolves to the very first item in 'foo.bars' array:

get(obj, 'foo.bars.{bak:1}.baz'); // => 1

It is also possible to use several fields in property lookup keys to resolve ambiguity:

get(obj, 'foo.bars.{bak:1,baz:2}.baz'); // => 2

Note, however, that lookup keys should be used with simple values since they uses == comparison.

Default Value

If the value resolved by get function is undefined, the default value, if provided, is returned in its place:

const obj = {foo: {bar: 'baz'}};
 
get(obj, 'foo.baz', 'bak'); // => 'bak';

Helpers

get-lookup also exports a set of helper functions related to it's internal logic, but that may come in handy sometimes:

import { isLookupKey, lookupIndex } from 'get-lookup';

• isLookupKey(key) - returns true if key represents a property lookup key.
• lookupIndex(array, key) - returns an integer index of the element of the given array that is identified by lookup key key. Returns -1 if no corresponding element is found.

Configuration

It is also possible to set custom value for lookup key term RegExp. A term is a part of the lookup key that represents property or value. Two terms together with semicolon between them represent a segment. One or more segments separated by commas and surrounded by curly braces represent lookup key itself.

To set custom term regular expression simply assign lookupTermRegExp property to get function itself:

import get, { isLookupKey } from 'get-lookup';
 
isLookupKey('{foo:b@r}'); // => false
 
get.lookupTermRegExp = /[\w\d@_-]+/;
 
isLookupKey('{foo:b@r}'); // => true

The default value for lookup key term regexp is /[\w\d_-]+/.

License

MIT