json config file to cmd opts string

configToOpts

#!/usr/local/bin/node

const fs = require('fs');

const configPath = process.argv[2];

fs.readFile(configPath, (err, data) => {
  if (err) {
    console.error(err);
    process.exit(1);
    return;
  }

  console.log(jsonToCmdOpts(data.toString()));
});

/**
 * Converts JSON objects into cmd option strings.
 * If an object property is 1 character it is assumed to be the short
 * opt syntax e.g. { "a": true, "all": true } ===> -a --all
 *
 * @param json {String}
 * @return {String}
 */
function jsonToCmdOpts(json) {
  let obj = JSON.parse(json);
  let opts = '';
  for (let prop in obj) {
    if (obj[prop] === false) continue;

    let delim = '=';
    if (prop.length === 1) opts += `-${prop}`;
    if (prop.length > 1) opts += `--${camelToKebab(prop)}`;
    if (prop.length === 0) delim = '';

    opts += typeof obj[prop] === 'boolean' ? ' ' : `${delim}${obj[prop]} `
  }
  return opts;
}

/**
 * Converts a string from camel case to kebab case
 * e.g. helloWorld ===> hello-world
 *
 * @param str {String}
 * @return {String}
 */
function camelToKebab(str) {
  return str.replace(/(?!^)([A-Z])/g, (m, p1) => '-'+p1.toLowerCase());
}