async-wrappers/esm/deferred.js

A set of wrapper functions to perform debouncing, throttling, retrying etc.

/**
 * @internal
 */

/**
 * @internal
 */
var deferred = callback => {
  var handle = null;
  var clear = clearTimeout;

  var call = () => {
    deferred.called = Date.now();
    deferred.delay = -1;
    callback();
  };

  var defer = delay => {
    delay = delay < 0 ? 0 : delay;
    deferred.deferred = Date.now();

    if (delay === 0 && deferred.delay === 0) {
      // if a delay is 0 it will happen on next execution.
      // so delaying a current delay of 0 should have no effect.
      // This is necessary here as a setTimeout implementation could
      // keep deferring execution, due to it's resolution issues.
      return;
    } // clear existing


    if (handle !== null) clear(handle);
    deferred.delay = delay;
    var useTimeout = !setImmediate || delay ? true : false;
    clear = useTimeout ? clearTimeout : clearImmediate;

    if (useTimeout) {
      handle = setTimeout(call, delay || 0);
    } else {
      handle = setImmediate(call);
    }
  };

  var cancel = () => {
    if (handle !== null) {
      deferred.delay = -1;
      clear(handle);
      handle = null;
    }
  };

  var deferred = {
    called: 0,
    deferred: 0,
    delay: -1,
    defer,
    cancel
  };
  return deferred;
};

export default deferred;