EpochDateTime.md

EpochDateTime

Namespace: SpawnDev.BlazorJS
Source: SpawnDev.BlazorJS/EpochDateTime.cs

EpochDateTime converts between .NET DateTime and JavaScript epoch milliseconds (milliseconds since 1970-01-01 UTC). It serializes to a JSON number (epoch milliseconds) and deserializes back to EpochDateTime. This is useful for JavaScript APIs that use numeric timestamps, such as Date.now(), performance.timeOrigin, or any API returning milliseconds since the Unix epoch.

Properties

Property	Type	Description
Value	DateTime	The DateTime value in local time (DateTimeKind.Local).
ValueEpoch	long	The epoch milliseconds (ms since 1970-01-01 UTC). Get or set.
Now	EpochDateTime	Static. Returns the current date/time as EpochDateTime.

Constructors

new EpochDateTime()                        // Default
new EpochDateTime(DateTime value)          // From DateTime
new EpochDateTime(long valueEpoch)         // From epoch milliseconds

Implicit Conversions

All conversions are implicit and bidirectional:

// DateTime <-> EpochDateTime
EpochDateTime epoch = DateTime.Now;
DateTime dt = epoch;

// DateTime? <-> EpochDateTime?
EpochDateTime? nullableEpoch = (DateTime?)null;
DateTime? nullableDt = (EpochDateTime?)null;

// long <-> EpochDateTime
EpochDateTime epoch = 1712345678000L;
long ms = epoch;

// long? <-> EpochDateTime?
EpochDateTime? nullableEpoch = (long?)null;
long? nullableMs = (EpochDateTime?)null;

Example

// Reading a JS timestamp
EpochDateTime created = jsObject.JSRef!.Get<EpochDateTime>("createdAt");
Console.WriteLine($"Created: {created.Value}");         // DateTime
Console.WriteLine($"Epoch ms: {created.ValueEpoch}");   // 1712345678000

// Setting a JS timestamp
jsObject.JSRef!.Set("expiresAt", EpochDateTime.Now);

// In a wrapper class
public class Token : JSObject
{
    public Token(IJSInProcessObjectReference _ref) : base(_ref) { }

    public EpochDateTime IssuedAt
    {
        get => JSRef!.Get<EpochDateTime>("iat");
        set => JSRef!.Set("iat", value);
    }

    public EpochDateTime ExpiresAt
    {
        get => JSRef!.Get<EpochDateTime>("exp");
        set => JSRef!.Set("exp", value);
    }
}

JSON Serialization

Serializes as a plain JSON number:

1712345678000

Deserializes from a number or null.