A script that analyses node_modules for stats of CJS and ESM usage

analyse-node_modules.sh

{
 CJS=0; ESM=0; DUAL=0; UN=0; UNP=''; TYPES=0;
 # for each `package.json` in the `node_modules` first and second levels:
 for P in $({
   ls node_modules/*/package.json;
   ls node_modules/*/*/package.json || true;
   ls node_modules/**/node_modules/*/package.json || true;
   ls node_modules/**/node_modules/*/*/package.json || true;
 } | sort); do
   echo "checking: $P";

   # unless the name implies it's a types project
   if [ "$P" = "${P/@types//}" ] && [ "$P" = "${P/-types}" ] && [ "$P" = "${P%/types/package.json}" ]; then 
     # find declared type from package.json:type
     T=$(node -p "require('./$P').type || 'null'");
     case "$T" in
       commonjs)
         CJS=$(( CJS + 1 ));;
       module)
         ESM=$(( ESM + 1));;
       null)
         #is it a dual support module?
         T=$(node -p "require('./$P').exports || 'null'");
 
         if [ ! "$T" = "null" ]; then
           # it has an exports section - count as dual support
           DUAL=$(( DUAL + 1 ));
         else # - need to take a peek in the main module
           # find the main module
           M=$(dirname "$P")/$(node -p "require('./$P').main || 'index.js'");
           # does the module expecting the sufix to be detected?
           [ -f "$M.js" ] && M="$M.js";
           [ -f "$M.mjs" ] && M="$M.mjs";
           # does the module name a directory, expecting the index to be detected?
           [ -f "$M/index.js" ] && M="$M/index.js";
           [ -f "$M/index.mjs" ] && M="$M/index.mjs";

           # count the cases, or count an unidentified
           if [ "'use strict'" = "$(grep . $M | sed 's/;//')" ]; #it's empty - its a stub for a types project
             then $(( TYPES + 1));
           elif grep -E 'require|module.exports|exports.' $M > /dev/null || [ -f "$M/index.json" ];
             then CJS=$(( CJS + 1 ));
           else # I give up. Count as unidentified.
             UN=$(( UN + 1)); UNP="$UNP,${P//node_modules\//}";
           fi
        fi;;
     esac;
   else TYPES=$(( TYPES + 1));
   fi
 done
 UNP="${UNP//\/package.json/}";
 echo -e "Unknown:
 ${UNP//,/\n - }
 
 Summary:
   CJS:    $CJS
   ESM:    $ESM
   DUAL:   $DUAL
   TYPES:  $TYPES
   Unkown: $UN
 ";
}