add list_indexof

[milahu]

could not find this function in list-utils.sh

function array_indexof() {
  [ $# -lt 2 ] && return 1
  local a=("$@")
  local v="${a[-1]}"
  unset a[-1]
  local i
  for i in ${!a[@]}; do
    if [ "${a[$i]}" = "$v" ]; then
      echo $i
      return 0 # stop after first match
    fi
  done
  return 1
}

a=(1 2 3 4)
i=$(array_indexof "${a[@]}" 3)
echo $i # 2

also posted on https://stackoverflow.com/a/70793702/10440128

similar:

// javascript
[1,2,3,4].indexOf(3) == 2

# python
[1,2,3,4].index(3) == 2