core.isvalidcronstring

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isValidCronString() function​

Returns true if the input is a cron expression the Medplum job scheduler can run.

Accepts what cron-parser accepts in its default, non-strict mode -- the @daily-style shorthands, month and weekday names, and the L, #, and ? extensions -- with these restrictions:

• The empty string, which cron-parser reads as every minute but BullMQ refuses as a missing pattern, is rejected. - An expression BullMQ cannot compute a next run for is rejected, since it would silently schedule nothing: one that can never fire, such as 0 0 31 4,6 *, or the 5th weekday of February, such as 0 0 * 2 1#5. - Schedules are limited to minute granularity, so the optional sixth (seconds) field and @secondly are rejected. - H (hashed) terms are rejected. They exist to stagger jobs that share a schedule; leaving them out keeps staggering an implementation detail of the scheduler and keeps the syntax authors of Cron and Bot resources must learn small. cron-parser also draws them at random, so one expression could pass on one parse and fail on the next.

Signature:

export declare function isValidCronString(cronString: string): boolean;

Parameters​

Returns:

boolean

True if the cron expression is valid.