[docs] Wrongly documented default props in controlled/uncontrolled components

[leonbloy]

Duplicates

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Latest version

• I have tested the latest version

Steps to reproduce 🕹

This applies to several components , I'll take Accordion as an example but it also applies eg to Checkbox

https://mui.com/material-ui/api/accordion/

Accordion has boolean two related input props: expanded defaultExpanded

The API docs says that both defaults to false.

This is wrong and misleading.

expanded defaults to undefined . Which is different (and is treated very differently) from false.

Precisely, MUI assumes that the component is uncontrolled if (and only if) expanded (the "controlled value", as in useControlled hook) is undefined .

If the docs were right, then writing <Accordion defaultExpanded /> (or equivalently <Accordion defaultExpanded ={true} /> would be the same as writing <Accordion defaultExpanded expanded={false} />- which obviously is not the case

Current behavior 😯

No response

Expected behavior 🤔

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Context 🔦

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Your environment 🌎

npx @mui/envinfo

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[hbjORbj]

This is indeed a bug. I will open a PR for a fix soon.

[hbjORbj]

but it also applies eg to Checkbox

Can you tell me which props of Checkbox you are referring to?

[leonbloy]

but it also applies eg to Checkbox

Can you tell me which props of Checkbox you are referring to?

checked and defaultChecked, they are equivalent to Accordion's expanded and defaultExpanded