Gathering detailed insights and metrics for reselect-map
Installations
npm install reselect-mapDeveloper Guide
BETA
Typescript
No
Module System
CommonJS
Node Version
15.0.1
NPM Version
7.0.3
Score
81.5
Supply Chain
99.6
Quality
75.4
Maintenance
100
Vulnerability
100
License
Releases
Unable to fetch releases
Contributors
5
Unable to fetch Contributors
Languages
2
JavaScript
TypeScript
JavaScript (92.55%)
TypeScript (7.45%)
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Developer
HeyImAlex
Download Statistics
Total Downloads
2,287,782
Last Day
422
Last Week
2,378
Last Month
10,687
Last Year
171,139
GitHub Statistics
MIT License
184 Stars
40 Commits
16 Forks
6 Watchers
18 Branches
5 Contributors
Updated on Mar 14, 2025
Bundle Size
5.05 kB
Minified
1.69 kB
Minified + Gzipped
Maintainers
1
Package Meta Information
Latest Version
1.0.6
Package Id
reselect-map@1.0.6
Unpacked Size
137.55 kB
Size
11.91 kB
File Count
10
NPM Version
7.0.3
Node Version
15.0.1
Total Downloads
Cumulative downloads
Total Downloads
2,287,782
Last Day
27.1%
422
Compared to previous day
Last Week
6.9%
2,378
Compared to previous week
Last Month
-3%
10,687
Compared to previous month
Last Year
-56.1%
171,139
Compared to previous year
Daily Downloads
Weekly Downloads
Monthly Downloads
Yearly Downloads
Peer Dependencies
1
reselect-map
Selectors for mapping over collections.
Installation
1npm install reselect-map reselect
Usage
This package exposes a few special selector creators. They're mostly the same as reselect's createSelector, with one major difference: the first dependency gets mapped over.
To give you a better idea, here's an example of how a selector to multiply an array of numbers would look in basic reselect and then using reselect-map.
1import { createSelector } from "reselect"; 2import { createArraySelector } from "reselect-map"; 3 4const exampleState = { 5 numbers: [1, 2, 3], 6 multiplier: 5, 7}; 8 9const numbers = (state) => state.numbers; 10const multiplier = (state) => state.multiplier; 11 12// reselect 13const mul1 = createSelector([numbers, multiplier], (numbers, multiplier) => 14 numbers.map((n) => n * multiplier) 15); 16 17// reselect-map 18const mul2 = createArraySelector( 19 [numbers, multiplier], 20 (number, multiplier) => number * multiplier 21); 22 23// Result: [5, 10, 15]
Notice the second version uses number instead of numbers; the result function is passed each element of numbers instead of the whole thing, and then the results are reassembled into an array.
So why would you use this? The answer is that you probably shouldn't! However, in certain situations it may significantly improve performance. Learn more in the motivation section.
API
The only thing to know is that the first dependency/selector passed is the one that gets mapped over, and all other selectors work just like they do in reselect proper. Additionally, key-based selectors like createObjectSelector and createMapSelector pass the key as the final argument.
NOTICE: This package makes use of the builtin Set and Map. If you need to support environments without Set or Map, you are going to have to polyfill it.
createArraySelector
Takes in an array, runs each element through the result function, and returns the results in a new array.
1import { createArraySelector } from "reselect-map"; 2 3const exampleState = { 4 numbers: [1, 2, 3], 5 multiplier: 5, 6}; 7 8const mul = createArraySelector( 9 (state) => state.numbers, 10 (state) => state.multiplier, 11 (number, multiplier) => number * multiplier 12); 13 14console.log(mul(exampleState)); // [5, 10, 15]
createObjectSelector
Takes an object, runs the value at each key through the result function, and returns an object with the results. The key is passed as the last argument to the selector function.
1import { createObjectSelector } from "reselect-map"; 2 3const exampleState = { 4 numbers: { a: 1, b: 2 }, 5 multiplier: 5, 6}; 7 8const mul = createObjectSelector( 9 (state) => state.numbers, 10 (state) => state.multiplier, 11 (number, multiplier, key) => `${key}:${number * multiplier}` 12); 13 14console.log(mul(exampleState)); // { a: 'a:5', b: 'b:10' }
createListSelector
Takes anything with an array-like map function, and returns whatever that returns. This conveniently makes it compatible with Immutable js collections and similar without erasing the input type.
1import { createListSelector } from "reselect-map"; 2import Immutable from "immutable"; 3 4const exampleState = { 5 numbers: Immutable.List([1, 2, 3]), 6 multiplier: 5, 7}; 8 9const mul = createListSelector( 10 (state) => state.numbers, 11 (state) => state.multiplier, 12 (number, multiplier) => number * multiplier 13); 14 15console.log(String(mul(exampleState))); // List [5, 10, 15]
createMapSelector
Like the sequence selector, but it expects the map function to provide a second argument to the callback that represents the key. This key is passed as the last argument to the selector function. This is mostly to support Immutable's Collection.Keyed types.
1import { createMapSelector } from "reselect-map"; 2import Immutable from "immutable"; 3 4const exampleState = { 5 numbers: Immutable.Map({ a: 1, b: 2 }), 6 multiplier: 5, 7}; 8 9const mul = createMapSelector( 10 (state) => state.numbers, 11 (state) => state.multiplier, 12 (number, multiplier, key) => `${key}:${number * multiplier}` 13); 14 15console.log(String(mul(exampleState))); // Map { "a": "a:5", "b": "b:10" }
Need more?
I'm hoping that what I've got here covers most common use cases, but it's not difficult to expand. Please let me know if there are any other selector types you'd like, or submit a pull request!
Motivation
When doing very expensive computations on elements of a collection, reselect might not give you the granularity of caching that you need. Imagine a selector that looks like this:
1import { createSelector } from "reselect"; 2 3const expensiveSelector = createSelector( 4 (state) => state.largeArray, 5 (largeArray) => largeArray.map(expensiveFunction) 6);
Notice that every time largeArray is changed, every single element of the array will be run back through expensiveFunction. If largeArray is very large or expensiveFunction is very expensive, this could be very slow.
What would be better is if we only recomputed those elements that are new or have changed. That's what this package does. Your expensiveFunction only runs on the elements it needs to.
When shouldn't you use reselect-map
When you don't need it. If your selector takes an array and multiplies every element by five (like in all of the examples), this package will slow your code down. In situations where you're having performance issues with reselect and you're thinking about how to cache on an element level, this package is here for you.
No vulnerabilities found.
Reason
no binaries found in the repo
Reason
license file detected
Details
- Info: project has a license file: LICENSE:0
- Info: FSF or OSI recognized license: MIT License: LICENSE:0
Reason
Found 3/26 approved changesets -- score normalized to 1
Reason
0 commit(s) and 0 issue activity found in the last 90 days -- score normalized to 0
Reason
no effort to earn an OpenSSF best practices badge detected
Reason
security policy file not detected
Details
- Warn: no security policy file detected
- Warn: no security file to analyze
- Warn: no security file to analyze
- Warn: no security file to analyze
Reason
project is not fuzzed
Details
- Warn: no fuzzer integrations found
Reason
branch protection not enabled on development/release branches
Details
- Warn: branch protection not enabled for branch 'master'
Reason
SAST tool is not run on all commits -- score normalized to 0
Details
- Warn: 0 commits out of 9 are checked with a SAST tool
Reason
26 existing vulnerabilities detected
Details
- Warn: Project is vulnerable to: GHSA-67hx-6x53-jw92
- Warn: Project is vulnerable to: GHSA-93q8-gq69-wqmw
- Warn: Project is vulnerable to: GHSA-grv7-fg5c-xmjg
- Warn: Project is vulnerable to: GHSA-w8qv-6jwh-64r5
- Warn: Project is vulnerable to: GHSA-3xgq-45jj-v275
- Warn: Project is vulnerable to: GHSA-w573-4hg7-7wgq
- Warn: Project is vulnerable to: GHSA-ww39-953v-wcq6
- Warn: Project is vulnerable to: GHSA-43f8-2h32-f4cj
- Warn: Project is vulnerable to: GHSA-896r-f27r-55mw
- Warn: Project is vulnerable to: GHSA-9c47-m6qq-7p4h
- Warn: Project is vulnerable to: GHSA-29mw-wpgm-hmr9
- Warn: Project is vulnerable to: GHSA-35jh-r3h4-6jhm
- Warn: Project is vulnerable to: GHSA-952p-6rrq-rcjv
- Warn: Project is vulnerable to: GHSA-f8q6-p94x-37v3
- Warn: Project is vulnerable to: GHSA-xvch-5gv4-984h
- Warn: Project is vulnerable to: GHSA-5fw9-fq32-wv5p
- Warn: Project is vulnerable to: GHSA-hj48-42vr-x3v9
- Warn: Project is vulnerable to: GHSA-hrpp-h998-j3pp
- Warn: Project is vulnerable to: GHSA-p8p7-x288-28g6
- Warn: Project is vulnerable to: GHSA-c2qf-rxjj-qqgw
- Warn: Project is vulnerable to: GHSA-jgrx-mgxx-jf9v
- Warn: Project is vulnerable to: GHSA-72xf-g2v4-qvf3
- Warn: Project is vulnerable to: GHSA-j8xg-fqg3-53r7
- Warn: Project is vulnerable to: GHSA-6fc8-4gx4-v693
- Warn: Project is vulnerable to: GHSA-3h5v-q93c-6h6q
- Warn: Project is vulnerable to: GHSA-c4w7-xm78-47vh
Score
1.9
/10
Last Scanned on 2025-03-10
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