Output all the violating rules as an array for turning off and turning on incrementally

eslint-error-formatter.js

module.exports = function (results) {
  const rulesFreqs = {};
  results.forEach(file => {
    file.messages.forEach(message => {
      if (!rulesFreqs[message.ruleId]) {
        rulesFreqs[message.ruleId] = 0;
      }
      rulesFreqs[message.ruleId] += 1;
    });
  });
  const ruleFreqsArray = Object.keys(rulesFreqs).map(rule => {
    return [rule, rulesFreqs[rule]];
  });
  ruleFreqsArray.sort((a, b) => {
    return a[1] - b[1];
  })
  let output = '';
  ruleFreqsArray.forEach(ruleFreq => {
    output += `${ruleFreq[0]}: ${ruleFreq[1]}\n`;
  })
  console.log(output);
}