Can I loop over the keys of an associative array with the same syntax as bash and zsh

I want to loop over the keys of an associative array, but I would like my script to work in zsh and bash. Would there be a way of doing it (syntax) that it would work in both

I know this

zsh:

for k in "${(k)array[@]}" do echo $k; done

bash:

for k in "${!array[@]}" do echo $k; done

Btw. I actually use oh-my-zsh, so I cannot really use something as emulate ksh, because it makes my terminal crash.

You can wrap each implementation in a function, and define only the function appropriate to the current shell:

if [[ $ZSH_VERSION ]]; then
  keys_for_array() {
    local array=$1 dest=$2
    [[ $1 && $2 ]] || { echo "Usage: keys_for_array source-array dest-array" >&2; return 1; }
    : ${(AP)dest::=${(kP)array}}
  }
elif [[ $BASH_VERSION && ! $BASH_VERSION =~ ^([123][.]|4[.][012]) ]]; then
  keys_for_array() {
    [[ $1 && $2 ]] || { echo "Usage: keys_for_array source-array dest-array" >&2; return 1; }
    local -n array=$1 dest=$2
    eval 'dest=( "${!array[@]}" )'
  }
else
  keys_for_array() { echo "ERROR: keys_for_array not available for this shell" >&2; return 1; }
fi

[[ $ZSH_VERSION ]] && typeset -A aa=( 1 one 2 two )
[[ $BASH_VERSION ]] && declare -A aa=( [1]=one [2]=two )
keys_for_array aa aak

declare -p aak

...when run on bash, output is:

declare -a aak=([0]="1" [1]="2")

...when run on zsh, output is:

typeset -a aak=( 1 2 )

In either case, you can then iterate over them:

keys_for_array aa aak
for key in "${aak[@]}"; do
  echo "Key $key has value ${aa[$key]}"
done

---

Note that above, both functions are syntactically valid in both shells. Otherwise, it might be necessary to use eval or source to pull them in only conditionally. Personally, I would create two separate files with both bash and zsh versions of your portability library, and source only the file appropriate to the current shell.