JavaScript utilities

string-util.js

import { Readable } from 'stream';

export function string2stream(stringOrBuffer) {
  const reader = new Readable();
  reader.push(stringOrBuffer);
  reader.push(null);
  return reader;
}

export function stream2buffer(stream) {
  return new Promise((resolve, reject) => {
    const chunks = [];
    stream.on('data', chunk => {
      chunks.push(chunk);
    });
    stream.on('end', () => {
      const buffer = Buffer.concat(chunks);
      resolve(buffer);
    });
    stream.on('error', e => {
      reject(e);
    });
  });
}

export function escapeRegExp(string) {
  return string.replace(/[.*+?^${}()|[\]\\]/g, '\\$&');
}

export function escapeHtml(string) {
  return string.replace(/[&<]/g, m => ({
    '&': '&amp;',
    '<': '&lt;',
  }[m]));
}

time-util.js

export function debounce(func, wait, options) {
  const { maxWait } = {
    ...options,
  };
  let startTime;
  let lastTime = 0;
  let timer;
  let callback;
  let result;
  wait = Math.max(0, +wait || 0);
  function checkTime() {
    timer = null;
    const now = performance.now();
    if (now >= startTime) {
      lastTime = now;
      callback();
    } else {
      checkTimer();
    }
  }
  function checkTimer() {
    if (!timer) {
      const delta = startTime - performance.now();
      timer = setTimeout(checkTime, delta);
    }
  }
  function debouncedFunction(...args) {
    const now = performance.now();
    startTime = maxWait && now < lastTime + maxWait ? lastTime + maxWait : now + wait;
    callback = () => {
      callback = null;
      lastTime = performance.now();
      result = func.apply(this, args);
    };
    checkTimer();
    return result;
  }
  return debouncedFunction;
}

export function throttle(func, wait) {
  let lastTime = 0;
  let result;
  wait = Math.max(0, +wait || 0);
  function throttledFunction(...args) {
    const now = performance.now();
    if (lastTime + wait < now) {
      lastTime = now;
      result = func.apply(this, args);
    }
    return result;
  }
  return throttledFunction;
}