function to get a random element of an array bash [duplicate]

This question already has an answer here:

• bash how to pass array as an argument to a function 4 answers

I have different arrays, representing the options of one function. I would like to randomize these options. I know how to get a random item from an array like that :

declare -a ARRAYISO=(100 200 400 800)
echo ${ARRAYISO["$[RANDOM % ${#ARRAYISO[@]}]"]}

I could obviously do that for each array, like a donkey, but I'd like to make a function taking an array as argument and return the random element.

I'm trying like that:

randArrayElement()
{
    randElement=${$1["$[RANDOM % ${#$1[@]}]"]} 
    echo  $randElement
}
randArrayElement ARRAYISO

but it doesn't like my $1... I've tryed with ", ', ` , bash doesn't interpret the $1 var...

Someone knows how to do that ?

Thanks, Mat