Polished date (ISO string) can have incorrect timezone offset applied

[bikerpatch]

On time series data returned from the API, the util.polish() routine may apply an incorrect timezone offset to the date time string when compared to the data["Meta Data"]["6. Time Zone"] attribute returned in the raw data.

Example

Tested on v2.3.0

Raw Response Notice the time zone is US/Eastern and that means the series key is 18th at 8pm Eastern time

{
    "Meta Data": {
        "1. Information": "Intraday (30min) open, high, low, close prices and volume",
        "2. Symbol": "MSFT",
        "3. Last Refreshed": "2022-07-18 20:00:00",
        "4. Interval": "30min",
        "5. Output Size": "Full size",
        "6. Time Zone": "US/Eastern"
    },
    "Time Series (30min)": {
        "2022-07-18 20:00:00": {
            "1. open": "254.6000",
            "2. high": "255.2000",
            "3. low": "254.6000",
            "4. close": "255.0200",
            "5. volume": "7262"
        },
...
}

Polished Response Notice the series key is 18th at 7pm with a Zulu zone, or UTC. This will mean a 5 hour difference to the correct time of the data point.

{
    "meta": {
        "information": "Intraday (30min) open, high, low, close prices and volume",
        "symbol": "MSFT",
        "updated": "2022-07-18 20:00:00",
        "interval": "30min",
        "size": "Full size",
        "zone": "US/Eastern"
    },
    "Time Series (30min)": {
        "2022-07-18T19:00:00.000Z": {
            "open": "254.6000",
            "high": "255.2000",
            "low": "254.6000",
            "close": "255.0200",
            "volume": "7262"
        },
...
}

Ideally the ISO string should contain the offset to UTC, e.g. 2022-07-18T20:00:00.000-04:00, so it can be correctly parsed.

Testing code

const alpha = require('alphavantage')({ key: 'mykey' });

alpha.data.intraday("MSFT", "full", "json", "30min").then((data) => {
    console.log(`data: ${JSON.stringify(data, null, 4)}`);

    console.log(`polish: ${JSON.stringify(alpha.util.polish(data), null, 4)}`);
}).catch((e) => {
    console.log(`e ${JSON.stringify(e, null, 4)}`)
})

[Phando]

Brilliant