EXJ(1)
  
  exj
  
  NAME
         exj - node.js standard input processor
  
  SYNOPSIS
         exj [OPTIONS] 'fn'
         exj [OPTIONS] -f | --file 'fnfile'

  DESCRIPTION
         Exj executes the given fn upon the standard input. Fn is expected to
         be a JavaScript function expression. The result of fn execution is 
         printed to standard output.
         
         If the result type of fn is a string, the result is printed directly
         to standard output.
        
         If the result type of fn is null or undefined, no action is taken.

         Any other result type is converted to JSON using JSON.stringify() and
         pretty-printed to standard output.
  
         If the result of fn is a Promise, the promise will be resolved and the
         result printed according to the above rules.

  GLOBALS
         EXEC
                A tagged template string which will execute escape and execute the contents as a child
                process, similar to running with -x

                EXAMPLE - print all files in the current directory:
                
                echo ls | exj -l 'x => EXEC`cat ${x}`'


  OPTIONS
         -j, --json
                Treat the input text as JSON. Input text will be parsed to
                JavaScript objects using JSON.parse() before being passed to fn.

         -p, --pretty
                Pretty print JSON output

         -l, --line
                Process each line of input separately. For each line of standard
                input, fn will be invoked for each line encountered, and the
                result will be written to standard output.

         -x, --exec
                Execute each output entry as a child process. The standard output
                of the finished process will be written to standard out.

                NOTE: Output entry MUST be an array of the format ['executable', 'arg1', 'arg2', ...]

         -f, --file 'fnfile'
                Read fn from a file, whose path is located at 'fnfile'.

         -g, --group-lines 'num'
                When processing lines, group batches of num lines together as an array

         -c, --concurrency 'num'
                When executing results via --exec option, execute at most num
                commands at once.

                Concurrency level also applies to awaiting of Promise results: no more lines
                of input will be processed while 'num' results are in flight.

         -r, --require package[:alias]
                An NPM package to be required into the namespace of 'fn', with optional alias

         --help
                Print usage text

  EXAMPLES
  
         ls | exj -l 'x => x.toUpperCase()'
                Print the contents of the current directory in uppercase
  
         curl https://jsonplaceholder.typicode.com/photos \
          | exj -j 'res => res.map((image) => `${image.title} - ${image.thumbnailUrl}`).join("\n")' | pbcopy
                Fetch and process a JSON payload of album artwork to the clipboard
  
         ls *.js | exj -lx 'x => ["mv", x, x.replace(/\.js$/, ".ts")]'
                convert javascript files to typescript

         cat urls.txt -l --concurrency 5 --require 'node-fetch:fetch' 'url => fetch(url).then(r => r.json())'
                Fetch the json contents of a list of URLs, fetching up to five URLs simultaneously

  SEE ALSO
         awk(1), jq(1), xargs(1)