Canonical fence language for an info string, or null if the block is not an FSL fence. Reads only the first whitespace-delimited token, case-insensitively.
null
The full fence info string (everything after the opening fence).
'fsl' or 'jssm' for our fences; null otherwise.
'fsl'
'jssm'
fsl_fence_lang('fsl image code') // => 'fsl' Copy
fsl_fence_lang('fsl image code') // => 'fsl'
fsl_fence_lang('JSSM') // => 'jssm' Copy
fsl_fence_lang('JSSM') // => 'jssm'
fsl_fence_lang('mermaid') // => null Copy
fsl_fence_lang('mermaid') // => null
Canonical fence language for an info string, or
nullif the block is not an FSL fence. Reads only the first whitespace-delimited token, case-insensitively.