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Tom Larkworthy
Tom Larkworthy

Posted on • Originally published at observablehq.com on

How to 1-of-n switch Dataflow streams on Observable

In this series, I will explore programming techniques for the notebook platform Observable. Today I am looking at how to direct a reactive Dataflow stream to one-of-n downstream cells. This article assumes you are familiar with Observable's non-linear reactive program flow already.

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Sometimes we want control the dataflow with logic. If we have a cell called data streaming values, we might like to direct those updates to either cell_1 or cell_2.

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You can programatically trigger dataflow by calling dispatchEvent on its enclosing view.

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You can create a lightweight view with Inputs.input

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Now dataflow is guided by the value of the choice variable.

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Give it a try on the live notebook at @tomlarkworthy/switch-dataflow

I hope you find that useful and that you find other useful ways to manipulate dataflow!

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