node/browserslistToTargets.js

const BROWSER_MAPPING = {
  and_chr: 'chrome',
  and_ff: 'firefox',
  ie_mob: 'ie',
  op_mob: 'opera',
  and_qq: null,
  and_uc: null,
  baidu: null,
  bb: null,
  kaios: null,
  op_mini: null,
};

function browserslistToTargets(browserslist) {
  let targets = {};
  for (let browser of browserslist) {
    let [name, v] = browser.split(' ');
    if (BROWSER_MAPPING[name] === null) {
      continue;
    }

    let version = parseVersion(v);
    if (version == null) {
      continue;
    }

    if (targets[name] == null || version < targets[name]) {
      targets[name] = version;
    }
  }

  return targets;
}

function parseVersion(version) {
  let [major, minor = 0, patch = 0] = version
    .split('-')[0]
    .split('.')
    .map(v => parseInt(v, 10));

  if (isNaN(major) || isNaN(minor) || isNaN(patch)) {
    return null;
  }

  return (major << 16) | (minor << 8) | patch;
}

module.exports = browserslistToTargets;