nexustate/src/NexustateHelpers.js

State management with listeners

import { assurePathExists, set } from 'objer';

export function findIndex(array, callback, context) {
  for (let keydex = 0; keydex < array.length; keydex += 1) {
    if (callback(array[keydex])) return keydex;
  }
  return -1;
}

// ** COPIED FROM UNDERSCORE JS **
// Returns a function, that, when invoked, will only be triggered at most once
// during a given window of time. Normally, the throttled function will run
// as much as it can, without ever going more than once per `wait` duration;
// but if you'd like to disable the execution on the leading edge, pass
// `{leading: false}`. To disable execution on the trailing edge, ditto.
export function throttle(func, wait, options) {
  var timeout, context, args, result;
  var previous = 0;
  if (!options) options = {};

  var later = function() {
    previous = options.leading === false ? 0 : new Date().getTime();
    timeout = null;
    result = func.apply(context, args);
    if (!timeout) context = args = null;
  };

  var throttled = function() {
    var now = new Date().getTime();
    if (!previous && options.leading === false) previous = now;
    var remaining = wait - (now - previous);
    context = this;
    args = arguments;
    if (remaining <= 0 || remaining > wait) {
      if (timeout) {
        clearTimeout(timeout);
        timeout = null;
      }
      previous = now;
      result = func.apply(context, args);
      if (!timeout) context = args = null;
    } else if (!timeout && options.trailing !== false) {
      timeout = setTimeout(later, remaining);
    }
    return result;
  };

  throttled.cancel = function() {
    clearTimeout(timeout);
    previous = 0;
    timeout = context = args = null;
  };

  return throttled;
}

export function getKeyFilledObject(key, value) {
  if (key === null) return value;
  const result = {};
  assurePathExists(result, key);
  set(result, key, value);
  return result;
}