# Request for advanced examples of CustomJS Callbacks

**URL:** <https://discourse.bokeh.org/t/request-for-advanced-examples-of-customjs-callbacks/7029>\
**Category:** Community Support\
**Tags:** browser, customjs\
**Created:** [January 11, 2021, 10:17pm UTC](https://discourse.bokeh.org/t/request-for-advanced-examples-of-customjs-callbacks/7029 "2021-01-11T22:17:12Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![CONSUMERTEC](https://discourse.bokeh.org/user_avatar/discourse.bokeh.org/consumertec/32/3033_2.png) [@CONSUMERTEC](https://discourse.bokeh.org/u/CONSUMERTEC)\
**Post date:** [January 11, 2021, 10:17pm UTC](https://discourse.bokeh.org/t/request-for-advanced-examples-of-customjs-callbacks/7029/1 "2021-01-11T22:17:12Z")

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First of all, congratulation for your development on Bokeh. I recently started to use it, it is a great tool.

My joob is to include analytical graphs inside a Flask app, and Bokeh seems a great option. I will really appreciate if you recommend me some advance examples or tutorials that cover the topic of using 2 or more widgets, multiple selection, to filter a large data set and interactively change the final plot, specially using CustomJS Callbacks, because it seems more easy to include the final script on some html file. The Gallery in the standalone section does not include this type of use.

Thank you in advance for your kind help.

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**Author:** ![Bryan](https://discourse.bokeh.org/user_avatar/discourse.bokeh.org/bryan/32/3625_2.png) [@Bryan](https://discourse.bokeh.org/u/Bryan)\
**Post date:** [January 12, 2021, 5:52pm UTC](https://discourse.bokeh.org/t/request-for-advanced-examples-of-customjs-callbacks/7029/2 "2021-01-12T17:52:24Z")

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@CONSUMERTEC have you seen this section of the User’s Guide?

> **[JavaScript callbacks](https://docs.bokeh.org/en/latest/docs/user_guide/interaction/callbacks.html)**
>
> While the main goal of Bokeh is to provide a path to create rich interactive visualizations in the browser purely from Python, there will always be specialized use-cases that are outside the capabi...

There are also many more examples than the gallery in the `examples` directory of the repo:

> **[bokeh/examples at branch-2.3 · bokeh/bokeh](https://github.com/bokeh/bokeh/tree/branch-2.3/examples)**
>
> branch-2.3/examples

You can search through those for `CustomJS` to find lot of examples that use callbacks.

It’s hard to know what else to suggest without specifics, and even so, most callback usage has the same general outline, regardless of how many widgets, etc:

- read widget values, `slider.value`, `picker.value` or whatever you have

- do some computation with those values

- modify some Bokeh objects (e.g. `source.data` or a CDS filter) to cause the page to update

Most of the “work” is in that middle bullet, but it’s not really Bokeh related or Bokeh specific, it just depends on what you in particular need to compute (in JavaScript)