npm package discovery and stats viewer.

Discover Tips

  • General search

    [free text search, go nuts!]

  • Package details

    pkg:[package-name]

  • User packages

    @[username]

Sponsor

Optimize Toolset

I’ve always been into building performant and accessible sites, but lately I’ve been taking it extremely seriously. So much so that I’ve been building a tool to help me optimize and monitor the sites that I build to make sure that I’m making an attempt to offer the best experience to those who visit them. If you’re into performant, accessible and SEO friendly sites, you might like it too! You can check it out at Optimize Toolset.

About

Hi, 👋, I’m Ryan Hefner  and I built this site for me, and you! The goal of this site was to provide an easy way for me to check the stats on my npm packages, both for prioritizing issues and updates, and to give me a little kick in the pants to keep up on stuff.

As I was building it, I realized that I was actually using the tool to build the tool, and figured I might as well put this out there and hopefully others will find it to be a fast and useful way to search and browse npm packages as I have.

If you’re interested in other things I’m working on, follow me on Twitter or check out the open source projects I’ve been publishing on GitHub.

I am also working on a Twitter bot for this site to tweet the most popular, newest, random packages from npm. Please follow that account now and it will start sending out packages soon–ish.

Open Software & Tools

This site wouldn’t be possible without the immense generosity and tireless efforts from the people who make contributions to the world and share their work via open source initiatives. Thank you 🙏

© 2024 – Pkg Stats / Ryan Hefner

selectorator

v4.0.3

Published

Simplified generator of reselect selectors

Downloads

66,678

Readme

selectorator

selectorator is an abstraction API for creating selectors via reselect with less boilerplate code.

Table of contents

Installation

$ npm i selectorator --save

Versions

Versions of selectorator on or above 3.x.x will use the corresponding major version of reselect as a dependency. If you wish to still use the 2.x.x branch of reselect for your application, then you should continue using the 1.x.x branch of selectorator.

If you would like to learn more about the breaking changes related to the major version change for reselect, please visit the reselect CHANGELOG.

Usage

import createSelector from "selectorator";

// selector created with single method call
const getBarBaz = createSelector(
  ["foo.bar", "baz"],
  (bar, baz) => {
    return `${bar} ${baz}`;
  }
);

const state = {
  foo: {
    bar: "bar"
  },
  baz: "baz"
};

console.log(getBarBaz(state)); // "bar baz"

Not a whole lot of magic here, just simplifying the creation of the "identity selectors" that reselect requires, instead replacing them with a standardized dot- or bracket-notation string for retrieval of a nested property in the state object.

That said, you can still use your own custom identity selectors, or compose selectors, if you so choose. Here is the example from the reselect README modified to use selectorator:

// subtotal built using simple method
const getSubtotal = createSelector(
  ["shop.items"],
  items => {
    return items.reduce((sum, { value }) => {
      return sum + value;
    }, 0);
  }
);

// tax builtrued with simple method combined with other selector
const getTax = createSelector(
  [getSubtotal, "shop.taxPercent"],
  (subtotal, taxPercent) => {
    return subtotal * (taxPercent / 100);
  }
);

// total build entirely with other selectors
const getTotal = createSelector(
  [getSubtotal, getTax],
  (subtotal, tax) => {
    return {
      total: subtotal + tax
    };
  }
);

const state = {
  shop: {
    taxPercent: 8,
    items: [{ name: "apple", value: 1.2 }, { name: "orange", value: 0.95 }]
  }
};

console.log("subtotal: ", getSubtotal(state)); // 2.15
console.log("tax: ", getTax(state)); // 0.172
console.log("total: ", getTotal(state)); // {total: 2.322}

Shorthand types

The following types of shorthand are available for parameter selector creation:

  • Pulls from state:
    • string => `'foo[0].bar'
    • number => 0
    • Array => ['foo', 0, 'bar']
  • Pulls from specific argument:
    • Object => {path: 'foo[0].bar', argIndex: 1}

Please note that the Object usage is the only approach that will allow for selection of parameters. All other shorthands will pull from the first parameter.

TypeScript

Selectorator now supports two optional type parameters, it accepts an Input type param (usually the redux state) and the expected output type.

When creating a selector that accepts multiple params, the state should be array of the input types example

i.e createSelector<[State, number[], boolean], string>

  import createSelector from "selectorator";

  interface State {
    foo: {
      bar: string;
    };
    baz: string;
  };
                        // State is input type, string is output type
  const getBarBaz = createSelector<State, string>(
    ["foo.bar", "baz"],
    (bar, baz) => {
      return `${bar} ${baz}`;
  });

  // getBarBaz() has type signature: (state: State) => string;

  const getBarBaz2 = createSelector<any, string>(
    ["foo.bar", "baz"],
    (bar, baz) => {
      return `${bar} ${baz}`;
  });

  // getBarBaz2() has type signature: (state: any) => string;

  const getBarBaz3 = createSelector(
    ["foo.bar", "baz"],
    (bar, baz) => {
      return `${bar} ${baz}`;
  });

  // getBarBaz3() has type signature: (state: any) => any;

  const getBarBaz4 = createSelector(
    ["foo.bar", "baz", { path: 0, argIndex: 2 }],
    (bar, baz) => {
      return `${bar} ${baz}`;
  });

  // getBarBaz4() has type signature: (...state: any[]) => any;

  const getBarBazQux5 = createSelector<[State, string[]], string>(
    ["foo.bar", "baz", { path: 0, argIndex: 2 }],
    (bar, baz) => {
      return `${bar} ${baz}`;
  });

  // getBarBaz5() has type signature: (state_0: State, state_1: string[]) => string;

  const getStucturedBarBaz = createSelector({
    barBaz: getBarBaz,
  });

  // getStructuredBarBaz() has type signature: (state: any) => ({ barBaz: string });

Options

All the capabilities that exist with reselect are still available using selectorator, they are just passed as an object of options to createSelector.

deepEqual

defaults to false

A common usage of custom selectors is to perform a deep equality check instead of the standard strict equality check when comparing values. To apply this, simply set deepEqual to true.

import createSelector from "selectorator";

const selectoratorOptions = {
  deepEqual: true
};

const getBaz = createSelector(
  ["foo.bar.baz"],
  baz => {
    return !!baz;
  },
  selectoratorOptions
);

isEqual

defaults to isSameValueZero

If you want to use a custom equality comparator, pass the method as this option.

import createSelector from "selectorator";

const selectoratorOptions = {
  // silly example checking current or next values related to "foo"
  isEqual(currentFoo, nextFoo) {
    return currentFoo === "foo" || nextFoo !== "foo";
  }
};

const getFoo = createSelector(
  ["foo"],
  foo => {
    return !!foo;
  },
  selectoratorOptions
);

Please note that if this parameter is provided and deepEqual is also set to true, deepEqual will take priority and the isEqual method will not be used.

memoizer

defaults to reselect defaultMemoize

If you want to use a custom memoizer, pass the method as this option. This will use createSelectorCreator from reselect internally, so consult their documentation on proper usage.

import createSelector from "selectorator";
import moize from "moize";

const selectoratorOptions = {
  memoizer: moize
};

const getFoo = createSelector(
  ["foo"],
  foo => {
    return !!foo;
  },
  selectoratorOptions
);

memoizerParams

defaults to []

reselect allows you to pass parameters to the memoizer function, and this array will translate directly into parameters 3-n. This is useful if your memoizer uses something other than direct comparison for its equality test.

import createSelector from "selectorator";

const selectoratorOptions = {
  memoizer: memoizerThatChecksEqualToEachOtherOrToSpecificValuePassed,
  memoizerParams: ["specificValue"]
};

const getFoo = createSelector(
  ["foo"],
  foo => {
    return !!foo;
  },
  selectoratorOptions
);

Development

Standard stuff, clone the repo and npm install dependencies. The npm scripts available:

  • build => run webpack to build development dist file with NODE_ENV=development
  • build:minifed => run webpack to build production dist file with NODE_ENV=production
  • dev => run webpack dev server to run example app (playground!)
  • docs => builds the docs via jsdoc
  • lint => run ESLint against all files in the src folder
  • prepublish => runs prepublish:compile
  • prepublish:compile => run lint, test:coverage, transpile, build, build:minified, and docs
  • test => run AVA test functions with NODE_ENV=test
  • test:coverage => run test but with nyc for coverage checker
  • test:watch => run test, but with persistent watcher
  • transpile => run babel against all files in src to create files in lib