JamieMason

const isAsyncFunction = fn => typeof fn === 'function' && fn.constructor.name === 'AsyncFunction';

JamieMason

const isPromiseLike = obj =>
  obj !== null &&
  (typeof obj === 'object' || typeof obj === 'function') &&
  typeof obj.then === 'function';

JamieMason

Format JavaScript Array of Strings to Oxford Comma

const toOxfordComma = (array) =>
  array.length === 2
    ? array.join(' and ')
    : array.length > 2
    ? array
        .slice(0, array.length - 1)
 .concat(`and ${array.slice(-1)}`)

JamieMason

Get Paths To Files In A Git Repository

Commands

added_in_branch

Files added (not modified or deleted) in our branch.

added_in_git_stage

Files added (not modified or deleted) in git add.

in_git_stage

Files in git add.

JamieMason

Get all changes from Git for the current Author

1. Get the Email of the current User/Developer/Author/Committer.
2. Resolve the Email through the Git Mailmap.
3. Get all files they have ever created or modified.
4. Get all files modified in the current branch compared to master.
5. Some files they've modified could have since been deleted by someone else, so filter out files which no longer exist.

Use Case

JamieMason

// Generally Expected Flow (actions and implementation are missing)
//
// 1 renderNode runs logic which inspects this hard-coded rootNode
// 2 transtions to renderBranch because it has children
// 3 there are two children so the UI would display them
// 4 user chooses the first child
// 5 fetchNode finds no children property, so there is nothing more to load
// 6 fetchNode resolves success with the node
// 7 renderNode runs logic which inspects the node
// 8 transtions to renderLeaf because it has no children

JamieMason

export default function transformer(file, api) {
  const j = api.jscodeshift;

  const toPascalCase = str =>
    `${str}`
      .replace(new RegExp(/[-_]+/, 'g'), ' ')
      .replace(new RegExp(/[^\w\s]/, 'g'), '')
      .replace(
        new RegExp(/\s+(.)(\w+)/, 'g'),
        ($1, $2, $3) => `${$2.toUpperCase() + $3.toLowerCase()}`

JamieMason

Pluck Unique Values from Array of Javascript Objects

Implementation

const pluck = key => array => Array.from(new Set(array.map(obj => obj[key])));

Usage

JamieMason

Group Array of JavaScript Objects by Key or Property Value

Implementation

const groupBy = key => array =>
  array.reduce((objectsByKeyValue, obj) => {
    const value = obj[key];
    objectsByKeyValue[value] = (objectsByKeyValue[value] || []).concat(obj);
    return objectsByKeyValue;

JamieMason

Learning about JavaScript Transducers

Work in progress sketch based on following along with the video course at https://egghead.io/courses/quickly-transform-data-with-transducers.

Source

const id = (value) => value;
const isArray = (value) => Array.isArray(value);
const isNumber = (value) => typeof value === 'number';