async-throttle-cache/dist/async-throttle-cache.cjs.js

Throttle or debounce asynchronous functions and return cached result for each function calls. It can be used for rate limit.

'use strict';

var returnSelf = function returnSelf(result) {
  return Promise.resolve(result);
};
function asyncThrottleCache(fn, wait, _temp) {
  if (wait === void 0) {
    wait = 0;
  }
  var _ref = _temp === void 0 ? {} : _temp,
    _ref$key = _ref.key,
    key = _ref$key === void 0 ? function () {
      for (var _len = arguments.length, args = new Array(_len), _key = 0; _key < _len; _key++) {
        args[_key] = arguments[_key];
      }
      return JSON.stringify(args);
    } : _ref$key,
    _ref$serialize = _ref.serialize,
    serialize = _ref$serialize === void 0 ? returnSelf : _ref$serialize,
    _ref$deserialize = _ref.deserialize,
    deserialize = _ref$deserialize === void 0 ? returnSelf : _ref$deserialize,
    _ref$debounce = _ref.debounce,
    debounce = _ref$debounce === void 0 ? undefined : _ref$debounce;
  var cache = {};
  var debounceLeading = debounce == null ? void 0 : debounce.leading;
  return function () {
    var _this = this;
    for (var _len2 = arguments.length, args = new Array(_len2), _key2 = 0; _key2 < _len2; _key2++) {
      args[_key2] = arguments[_key2];
    }
    // eslint-disable-line func-names
    var cacheKey = key.apply(void 0, args);
    var cached = cache[cacheKey];
    var onFinish = function onFinish(index, err, result) {
      var cachedF = cache[cacheKey];
      if ((cachedF == null ? void 0 : cachedF.i) === index) {
        cachedF.f = true;
        if (err) {
          cachedF.e = err;
          cachedF.j.map(function (f) {
            return f(err);
          });
        } else {
          serialize(result).then(function (r) {
            cachedF.r = r;
            cachedF.s.map(function (f, i) {
              return deserialize(r).then(f, cachedF.j[i]);
            });
          }, onFinish);
        }
        if (!cachedF.t || debounce && !debounceLeading) {
          delete cache[cacheKey];
        }
      }
      return result;
    };
    var exec = function exec() {
      var cachedE = cache[cacheKey];
      var i = cachedE.i = Date.now();
      cachedE.f = false;
      return fn.apply(_this, args).then(function (result) {
        return onFinish(i, undefined, result);
      }, function (err) {
        onFinish(i, err);
        return Promise.reject(err);
      });
    };
    var timeout = function timeout() {
      return setTimeout(function () {
        var cachedT = cache[cacheKey];
        if (cachedT) {
          if (debounce && cachedT.s.length) {
            exec();
          } else if (cachedT.f) {
            delete cache[cacheKey];
          } else {
            cachedT.t = 0;
          }
        }
      }, wait);
    };
    var padding = function padding() {
      return new Promise(function (resolve, reject) {
        var cachedP = cache[cacheKey];
        cachedP.s.push(resolve);
        cachedP.j.push(reject);
      });
    };
    if (cached) {
      if (debounce) {
        clearTimeout(cached.t);
        cached.t = timeout();
      } else {
        var e = cached.e,
          r = cached.r,
          f = cached.f;
        if (e !== undefined) {
          return Promise.reject(e);
        }
        if (f) {
          return deserialize(r);
        }
      }
      return padding();
    }
    cache[cacheKey] = {
      s: [],
      // resolve callbacks
      j: [],
      // reject callbacks
      t: timeout()
    };
    return !debounce || debounceLeading ? exec() : padding();
  };
}

module.exports = asyncThrottleCache;