iep-ui/lib/vc-util/Dom/throttle-debounce.js

An enterprise-class UI design language and Vue-based implementation

'use strict';

Object.defineProperty(exports, "__esModule", {
  value: true
});
function throttle(delay, noTrailing, callback, debounceMode) {
  var timeoutID = void 0;
  var cancelled = false; // Keep track of the last time `callback` was executed.

  var lastExec = 0; // Function to clear existing timeout

  function clearExistingTimeout() {
    if (timeoutID) {
      clearTimeout(timeoutID);
    }
  } // Function to cancel next exec

  function cancel() {
    clearExistingTimeout();
    cancelled = true;
  } // `noTrailing` defaults to falsy.

  if (typeof noTrailing !== 'boolean') {
    debounceMode = callback;
    callback = noTrailing;
    noTrailing = undefined;
  }

  function wrapper() {
    for (var _len = arguments.length, arguments_ = new Array(_len), _key = 0; _key < _len; _key++) {
      arguments_[_key] = arguments[_key];
    }

    var self = this;
    var elapsed = Date.now() - lastExec;

    if (cancelled) {
      return;
    } // Execute `callback` and update the `lastExec` timestamp.

    function exec() {
      lastExec = Date.now();
      callback.apply(self, arguments_);
    }
    /*
     * If `debounceMode` is true (at begin) this is used to clear the flag
     * to allow future `callback` executions.
     */

    function clear() {
      timeoutID = undefined;
    }

    if (debounceMode && !timeoutID) {
      /*
       * Since `wrapper` is being called for the first time and
       * `debounceMode` is true (at begin), execute `callback`.
       */
      exec();
    }

    clearExistingTimeout();

    if (debounceMode === undefined && elapsed > delay) {
      /*
       * In throttle mode, if `delay` time has been exceeded, execute
       * `callback`.
       */
      exec();
    } else if (noTrailing !== true) {
      /*
       * In trailing throttle mode, since `delay` time has not been
       * exceeded, schedule `callback` to execute `delay` ms after most
       * recent execution.
       *
       * If `debounceMode` is true (at begin), schedule `clear` to execute
       * after `delay` ms.
       *
       * If `debounceMode` is false (at end), schedule `callback` to
       * execute after `delay` ms.
       */
      timeoutID = setTimeout(debounceMode ? clear : exec, debounceMode === undefined ? delay - elapsed : delay);
    }
  }

  wrapper.cancel = cancel; // Return the wrapper function.

  return wrapper;
}
function debounce(delay, atBegin, callback) {
  return callback === undefined ? throttle(delay, atBegin, false) : throttle(delay, callback, atBegin !== false);
}

exports.debounce = debounce;
exports.throttle = throttle;