Given a variable a (non array) or (any[]) convert to (any[])
function example(s: string | string[]) {
const e = Array.isArray(s) ? s: [s]
return e
}
Is Array.isArray(s) ? s: [s] the shortest way?
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5\$\begingroup\$ Welcome to Code Golf! I've added the tips tag, since this is asking for a way to shorten some code in a specific language. \$\endgroup\$– Rydwolf ProgramsJan 22, 2022 at 6:12
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\$\begingroup\$ Do you know a concrete type if the value isn't an array? \$\endgroup\$– codeJun 25, 2022 at 2:19
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2 Answers
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10 bytes
[s].flat()
This works by doing a shallow flat on [s]. So, if s is anything other than an array, nothing can be flattened and it will stay as [s]. But if s is an array, the outer [] will be flattened away, leaving a shallow clone of s.
Note that you can also use this to concat a number of arrays, either with other arrays or non-array elements:
[r,s,t].flat()
This is actually a trick I wasn't aware of until now. It's still a byte longer than concat though, if the first item's guaranteed to be an array:
r.concat(s,t)
When r could be anything, [r,s,t].flat() seems to be the best option.
answered Jan 22, 2022 at 6:18
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1\$\begingroup\$ In older versions you can still write
[].concat(r,s,t). \$\endgroup\$– NeilJan 22, 2022 at 7:20
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aparently this works t.map?t:[t]
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10\$\begingroup\$ Works, but risky.
tmight be a different type of object with amapproperty. If you want to go down this route,t.to?t:[t]would also work in a modern browser \$\endgroup\$– jonrandyJan 22, 2022 at 6:22