Useful code snippets in JavaScript

utils.js

const fs = require("fs-extra");
const Path = require("path");

//
// String utilities
//

// Ensure initial letter is capitalized
const capitalize = word => word[0].toUpperCase() + word.substr(1);

// Strip newlines from string
const stripCRLF = s => s.replace(/\r?\n|\r/g, "");

// Truncate text with an ellipse
const ellipse = (str, max = 200) => {
  if (str.length > max) {
    return str.substring(0, max) + "...";
  }
  return str;
};

const parseTime = time => {
  const currentDateString = new Date().toISOString();
  return new Date(
    currentDateString.substr(0, currentDateString.indexOf("T") + 1) + time
  );
};

/**
 * Update the set of values for this indexed collection
 */
const append = (obj, k, v) => {
  let e = obj[k];
  if (!e || e.length === 0) obj[k] = e = [];
  e.push(v);
  return e;
};

//
// Object utilities
//
/**
 * Ensure an entry exists in a dictionary
 */
const getOrSet = (obj, k, v) => {
  let e = obj[k];
  if (!e) obj[k] = e = v;
  return e;
};

/**
 * Emptiness test
 */
const isNullOrEmpty = obj => {
  if (obj === null || obj === undefined) return true;

  const type = typeof obj;
  if (type === "object") {
    if (Array.isArray(obj)) {
      return obj.length === 0;
    }
    return Object.keys(obj).length === 0;
  }

  if (type === "string") {
    return obj === "";
  }

  return false;
};

//
// File utilities
//

/**
 * Find all files inside a dir, recursively.
 * @param  {string} dir Dir path string.
 * @return {string[]} Array with all file names that are inside the directory.
 */
const findAllFiles = dir =>
  fs.readdirSync(dir).reduce((files, file) => {
    const name = Path.join(dir, file);
    const isDirectory = fs.statSync(name).isDirectory();
    return isDirectory ? [...files, ...findAllFiles(name)] : [...files, name];
  }, []);

/**
 * Synchronously read an entire UTF-8 encoded file, stripping initial BOM
 * code, if present
 * @param {file} file
 * @return {text}
 */
const readFile = file => {
  if (!file) {
    throw new Error("No file specifed for read");
  }

  let text = fs.readFileSync(file, "utf-8");
  if (!text) {
    throw new Error(`No text in file: ${file}`);
  }

  // Catches EFBBBF (UTF-8 BOM) because the buffer-to-string
  // conversion translates it to FEFF (UTF-16 BOM)
  if (text.charCodeAt(0) === 0xfeff) {
    text = text.slice(1);
  }
  return text;
};

const parseJSONFile = file => {
  return JSON.parse(readFile(file));
};

module.exports = {
  capitalize,
  stripCRLF,
  ellipse,
  parseTime,
  append,
  getOrSet,
  isNullOrEmpty,
  findAllFiles,
  readFile,
  parseJSONFile
};