Set CSS Properties based on JSON data from DatoCMS

dato.config.js

// dato.config.js

var fs = require('fs');

module.exports = (dato, root, i18n) => {

  // Modify SCSS properties in public/assets/css/colors.scss
  // -------------------------------------------------------
  // The file to modify
  var file = 'public/assets/css/colors.scss';
  // Find properties and assign new values
  var properties = {
    '$primary-color': dato.brand.primaryColor,
    '$secondary-color': dato.brand.secondaryColor,
    '$tertiary-color': dato.brand.tertiaryColor
  };
  // Write the changes to the file (omit properties to reset to default)
  setCssProperties(file, properties);

};

function setCssProperties(file, properties) {
  // The file to modify or set the default file
  var file = file || 'public/assets/css/colors.scss';
  // Find properties and assign new values or provide defaults
  var properties = properties || {
    '$primary-color': '#13c0d7',
    '$secondary-color': '#8dc63f',
    '$tertiary-color': '#f0bc00'
  };

  // Read file
  fs.readFile(file, 'utf8', function (err,data) {
    if (err) return console.log(err);

    // Replace properties with regular expressions
    var pattern = '';
    var value = '';
    var replace_str = '';

    // Perform replacements on result
    var result = data;

    for (property in properties) {
      // Build replacement strings for each property
      pattern = '(\\' + property + ':)(.+?);';
      value = properties[property];
      replace_str = property + ': ' + value + ';'
      // Replace the matching properties in the file
      result = result.replace(RegExp(pattern, 'g'), replace_str);
    }

    // Write file
    fs.writeFile(file, result, 'utf8', function (err) {
       if (err) return console.log(err);
    });
    // Log change to console
    console.log("\n* Written " + file);
  });
}