Demonstrates building rich completion via yargs

yargs-completion-demo.ts

import yargs, { Arguments } from 'yargs';
import fs from 'fs';

export const cli = yargs(process.argv)
  .scriptName('confluence-sync')
  .usage('$0 <command> [options]')
  .demandCommand(1, 'You need to specify a command')
  .completion('completion', (current: string, argv: Arguments<any>, completionFilter, done) => {
      const [_, command] = argv._;
      /**
       * First check to see if the user is actively typing
       * a valid command. commands for this
       * program are 'sync' and 'download'.
       */
      const completions = ['sync', 'download']
        .filter(c => c.startsWith(command));
      switch (command) {
        case "sync":
          {
            /** If --destination is provided, then
             * we can provide the file path completion
             */
            if ("destination" in argv || "d" in argv) {
              completionFilter(() => {
                const sourcePath = process.cwd();
                if (fs.existsSync(sourcePath)) {
                  const stats = fs.statSync(sourcePath);
                  if (stats.isDirectory()) {
                    const keys = fs.readdirSync(sourcePath);
                    done(keys);
                  }
                }
              });
            }
            break;
          }
        case "download":
          {
            /** If --source is provided, then
             * we can provide the file path completion
             */
            if ("source" in argv || "s" in argv) {
              completionFilter(() => {
                const sourcePath = process.cwd();
                if (fs.existsSync(sourcePath)) {
                  const stats = fs.statSync(sourcePath);
                  if (stats.isDirectory()) {
                    const keys = fs.readdirSync(sourcePath);
                    done(keys);
                  }
                }
              });
            }
            break;
          }
        default: {
          completionFilter(() => done(completions));
        }
      }
  })
  .strict()
  .help()
  .alias('h', 'help')
  .version()
  .alias('v', 'version');