Method futuresChart

src/node-binance-api.ts:5805–5860

* Websocket futures klines * @param {array/string} symbols - an array or string of symbols to query * @param {string} interval - the time interval * @param {function} callback - callback function * @param {int} limit - maximum results, no more than 1000 * @return {string} th

(symbols: string[] | string, interval: Interval, callback: Callback, limit = 500)

     * @return {string} the websocket endpoint
     */
    futuresChart(symbols: string[] | string, interval: Interval, callback: Callback, limit = 500) {
        const reconnect = () => {
            if (this.Options.reconnect) this.futuresChart(symbols, interval, callback, limit);
        };

        const futuresChartInit = (symbol: string) => {
            if (typeof this.futuresMeta[symbol] === 'undefined') this.futuresMeta[symbol] = {};
            if (typeof this.futuresMeta[symbol][interval] === 'undefined') this.futuresMeta[symbol][interval] = {};
            if (typeof this.futuresTicks[symbol] === 'undefined') this.futuresTicks[symbol] = {};
            if (typeof this.futuresTicks[symbol][interval] === 'undefined') this.futuresTicks[symbol][interval] = {};
            if (typeof this.futuresRealtime[symbol] === 'undefined') this.futuresRealtime[symbol] = {};
            if (typeof this.futuresRealtime[symbol][interval] === 'undefined') this.futuresRealtime[symbol][interval] = {};
            if (typeof this.futuresKlineQueue[symbol] === 'undefined') this.futuresKlineQueue[symbol] = {};
            if (typeof this.futuresKlineQueue[symbol][interval] === 'undefined') this.futuresKlineQueue[symbol][interval] = [];
            this.futuresMeta[symbol][interval].timestamp = 0;
        };

        const handleFuturesKlineStream = kline => {
            const symbol = kline.s, interval: Interval = kline.k.i;
            if (!this.futuresMeta[symbol][interval].timestamp) {
                if (typeof (this.futuresKlineQueue[symbol][interval]) !== 'undefined' && kline !== null) {
                    this.futuresKlineQueue[symbol][interval].push(kline);
                }
            } else {
                //this.options.log('futures klines at ' + kline.k.t);
                this.futuresKlineHandler(symbol, kline);
                if (callback) callback(symbol, interval, this.futuresKlineConcat(symbol, interval));
            }
        };

        const getFuturesKlineSnapshot = async (symbol: string, limit = 500) => {
            const data = await this.publicFuturesRequest('v1/klines', { symbol, interval, limit });
            this.futuresKlineData(symbol, interval, data);
            //this.options.log('/futures klines at ' + this.futuresMeta[symbol][interval].timestamp);
            if (typeof this.futuresKlineQueue[symbol][interval] !== 'undefined') {
                for (const kline of this.futuresKlineQueue[symbol][interval]) this.futuresKlineHandler(symbol, kline, this.futuresMeta[symbol][interval].timestamp);
                delete this.futuresKlineQueue[symbol][interval];
            }
            if (callback) callback(symbol, interval, this.futuresKlineConcat(symbol, interval));
        };

        let subscription;
        if (Array.isArray(symbols)) {
            if (!this.isArrayUnique(symbols)) throw Error('futuresChart: "symbols" array cannot contain duplicate elements.');
            symbols.forEach(futuresChartInit);
            const streams = symbols.map(symbol => `${symbol.toLowerCase()}@kline_${interval}`);
            subscription = this.futuresSubscribe(streams, handleFuturesKlineStream, reconnect);
            symbols.forEach(element => getFuturesKlineSnapshot(element, limit));
        } else {
            const symbol = symbols;
            futuresChartInit(symbol);
            subscription = this.futuresSubscribeSingle(symbol.toLowerCase() + '@kline_' + interval, handleFuturesKlineStream, { reconnect });
            getFuturesKlineSnapshot(symbol, limit);
        }
        return (subscription as any).url;
    }

    /**