@markedjs/html-differ/lib/logger.js

Compares two HTML

import chalk from 'chalk';
const inverseGreen = chalk.green.inverse;
const inverseRed = chalk.red.inverse;
const grey = chalk.grey;

/**
 * @typedef {Object} Diff
 * @property {String} value
 * @property {String|undefined} added
 * @property {String|undefined} removed
 */

/**
 * Returns readable diff text
 * @param {Diff[]} diff
 * @param {Object} [options]
 * @param {Number} [options.charsAroundDiff=40]
 * @returns {String}
 */
export function getDiffText(diff, options) {
  options = options || {
    charsAroundDiff: 40,
  };

  let charsAroundDiff = options.charsAroundDiff,
    output = '';

  if (charsAroundDiff < 0) {
    charsAroundDiff = 40;
  }

  if (diff.length === 1 && !diff[0].added && !diff[0].removed) return output;

  diff.forEach(function(part) {
    const index = diff.indexOf(part);
    const partValue = part.value;
    let diffColor;

    if (part.added) diffColor = inverseGreen;
    if (part.removed) diffColor = inverseRed;

    if (diffColor) {
      output += (index === 0 ? '\n' : '') + diffColor(partValue);

      return;
    }

    if (partValue.length < charsAroundDiff * 2) {
      output += (index !== 0 ? '' : '\n') + grey(partValue);
    } else {
      if (index !== 0) {
        output += grey(partValue.substr(0, charsAroundDiff));
      }

      if (index < diff.length - 1) {
        output += '\n...\n' + grey(partValue.substr(partValue.length - charsAroundDiff));
      }
    }
  });

  return output;
}

/* istanbul ignore next */
/**
 * Logs the diff of the given HTML docs to the console
 * @param {Object[]} diff
 * @param {Object} [options]
 * @param {Number} [options.charsAroundDiff=40]
 */
export function logDiffText(diff, options) {
  const diffText = getDiffText(diff, options);

  if (diffText) {
    console.log(inverseGreen('+ expected'), inverseRed('- actual'), '\n', diffText);
    return false;
  }

  return true;
}