Document how $WEB_EXT_PREF works

[kumar303]

How does setting the $WEB_EXT_PREF environment variable work when setting multiple preference values? Once we figure it out, let's update the docs: https://developer.mozilla.org/en-US/Add-ons/WebExtensions/web-ext_command_reference?document_saved=true#--pref

[rpl]

@kumar303 These are the relevant pieces from the yargs sources:

• https://github.com/yargs/yargs-parser/blob/68d68a0440510eabbd4d1aca22b6b091e454c19f/index.js#L486-L505
• https://github.com/yargs/yargs-parser/blob/68d68a0440510eabbd4d1aca22b6b091e454c19f/test/yargs-parser.js#L1608-L1777

it looks like nested keys are supported, but unfortunately multiple instances of the same option is not a supported scenario :-(

[kumar303]

We might need to support a colon here after all just for environment variable support :) Something like:

export WEB_EXT_PREF="first.pref=value:second.pref=true"

[Natim]

You can use the --pref option multiple times:

web-ext run -s build/ --pref intl.locale.requested=ar --pref intl.locale.matchOS=false  --pref general.useragent.locale=ar