Useful JS scripts and snippets

debounce.js

const debounce = (func, delay) => {
  let inDebounce;
  
  return function() {
    const context = this;
    const args = arguments;
    
    clearTimeout(inDebounce);
    
    inDebounce = setTimeout(() => func.apply(context, args), delay);
  }
}

// usage: debounce(() => { console.log('debounced'); }, 1000);

getUrlParam.js

// inspired by https://davidwalsh.name/query-string-javascript

function getURLParam(param) {
  return (
    decodeURIComponent(
      (new RegExp(
        '[?|&]' + param + '=' + '([^&;]+?)(&|#|;|$)'
      ).exec(location.search) || [, ''])[1].replace(/\+/g, '%20')
    ) || null
  );
}

// Usage: getURLParam('q')



/*
 * Updated using URLSearchParam
 */
 
const searchParam = new URLSearchParams(location.search);
searchParam.get('q');

throttle.js

const throttle = (func, limit) => {
  let inThrottle;
  
  return function() {
    const args = arguments;
    const context = this;
    
    if (!inThrottle) {
      func.apply(context, args);
      inThrottle = true;
      setTimeout(() => inThrottle = false, limit);
    }
  }
}

// usage: throttle(() => { console.log('throttled') }, 200);

walker.js

// recursive path walker
function walk(dir, extension, done) {
  let results = [];
  
  fs.readdir(dir, (err, list) => {
    if (err) return done(err);
    let pending = list.length;
    if (!pending) return done(null, results);
    list.forEach(file => {
      file = path.resolve(dir, file);
      fs.stat(file, (err, stat) => {
        if (stat && stat.isDirectory()) {
          walk(file, extension, (err, res) => {
            results = results.concat(res);
            if (!--pending) done(null, results);
          });
        } else {
          if (file.substr(file.lastIndexOf('.') + 1, file.length).toLowerCase() === extension) results.push(file);
          if (!--pending) done(null, results);
        }
      });
    });
  });
}

// usage
walk(
  path.resolve('./dev/'),
  'js',
  (err, results) => {
    // results is the array of files
    console.log(results);

    if (err) console.error(err);
  }
);