represents an expression whose evaluation is delayed until its value is externally requested.


specifies that the result from evaluating expr should be given in format fmt.


specifies that the result should be given as a response of the form rform.

Details and Options


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Basic Examples  (1)

Delayed specifies that the expression should not be evaluated until it is requested:

This link gives the current time. Revisiting the link gives the new time:

Options  (2)

CachePersistence  (1)

Deploy a Delayed that gives the current time and caches its result for up to 3 seconds:

UpdateInterval  (1)

Deploy a Delayed that refreshes every 3 seconds when displayed in a web browser:

Possible Issues  (1)

Since the default ExportForm of Delayed[expr] is HTMLFragment, an expression evaluating to None will be returned as an empty string:

In order to get the correct value in the above example, specify the format of Delayed[expr] as Wolfram Language:

Wolfram Research (2014), Delayed, Wolfram Language function, (updated 2014).


Wolfram Research (2014), Delayed, Wolfram Language function, (updated 2014).


Wolfram Language. 2014. "Delayed." Wolfram Language & System Documentation Center. Wolfram Research. Last Modified 2014.


Wolfram Language. (2014). Delayed. Wolfram Language & System Documentation Center. Retrieved from


@misc{reference.wolfram_2024_delayed, author="Wolfram Research", title="{Delayed}", year="2014", howpublished="\url{}", note=[Accessed: 25-July-2024 ]}


@online{reference.wolfram_2024_delayed, organization={Wolfram Research}, title={Delayed}, year={2014}, url={}, note=[Accessed: 25-July-2024 ]}