@ars9/decay/lib/index.js

A library for numeric values decaying with time

"use strict";
var __extends = (this && this.__extends) || (function () {
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    return function (d, b) {
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})();
var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, generator) {
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var __importDefault = (this && this.__importDefault) || function (mod) {
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};
Object.defineProperty(exports, "__esModule", { value: true });
exports.Decay = exports.DecayType = void 0;
var events_1 = __importDefault(require("events"));
var DecayType;
(function (DecayType) {
    DecayType[DecayType["Linear"] = 0] = "Linear";
    DecayType[DecayType["Exponential"] = 1] = "Exponential";
})(DecayType = exports.DecayType || (exports.DecayType = {}));
var Decay = (function (_super) {
    __extends(Decay, _super);
    function Decay(config) {
        var _this = _super.call(this) || this;
        if (!config) {
            config = {};
        }
        _this._value =
            config.initialValue !== undefined ? Number(config.initialValue) : 1;
        _this.decayValue =
            config.decayValue !== undefined ? Number(config.decayValue) : 1;
        _this.minValue = config.minValue !== undefined ? Number(config.minValue) : 0;
        _this.maxValue =
            config.maxValue !== undefined ? Number(config.maxValue) : Infinity;
        _this.interval =
            config.interval !== undefined ? Number(config.interval) : 1000;
        _this.type = config.type !== undefined ? config.type : DecayType.Linear;
        _this.iter = 0;
        return _this;
    }
    Decay.prototype.increment = function (value) {
        this.value += value !== undefined ? value : this.decayValue;
    };
    Decay.prototype.decrement = function (value) {
        this.value -= value !== undefined ? value : this.decayValue;
    };
    Object.defineProperty(Decay.prototype, "value", {
        get: function () {
            return this._value;
        },
        set: function (newValue) {
            this._value = Number(newValue);
            this.enforceMinMax();
        },
        enumerable: false,
        configurable: true
    });
    Decay.prototype.start = function () {
        var _this = this;
        this.timer = setInterval(function () { return _this.tick(); }, this.interval);
        this.emit('start', this.value);
    };
    Decay.prototype.stop = function () {
        this.iter = 0;
        if (this.timer) {
            clearInterval(this.timer);
        }
        this.emit('stop', this.value);
        return this.value;
    };
    Decay.prototype.wait = function () {
        return __awaiter(this, void 0, void 0, function () {
            var _this = this;
            return __generator(this, function (_a) {
                return [2, new Promise(function (resolve, reject) {
                        if (!_this.timer) {
                            reject();
                        }
                        var resolver = function (v) {
                            _this.removeListener('min', resolver);
                            _this.removeListener('max', resolver);
                            _this.removeListener('stop', resolver);
                            resolve(v);
                        };
                        _this.once('min', resolver);
                        _this.once('max', resolver);
                        _this.once('stop', resolver);
                    })];
            });
        });
    };
    Decay.prototype.tick = function () {
        if (this.type === DecayType.Exponential) {
            this.value -= this.decayValue * Math.pow(Math.E, this.iter);
        }
        else {
            this.value -= this.decayValue;
        }
        this.iter++;
    };
    Decay.prototype.enforceMinMax = function () {
        if (this.value > this.maxValue) {
            this.value = this.maxValue;
            this.emit('max', this.value);
            this.iter = 0;
        }
        if (this.value < this.minValue) {
            this.value = this.minValue;
            this.emit('min', this.value);
            this.iter = 0;
        }
    };
    return Decay;
}(events_1.default));
exports.Decay = Decay;