An example of custom function for node-sass

[ajhsu]

const nodeSass = require('node-sass');

console.log(
  nodeSass.renderSync({
    data: '#{headings(2,5)} { color: #08c; }',
    functions: {
      // 0 and 6 are default values
      'headings($from: 0, $to: 6)': function(from, to) {
        console.log(from.getValue(), to.getValue())
        var i,
          f = from.getValue(),
          t = to.getValue(),
          list = new nodeSass.types.List(t - f + 1);

        for (i = f; i <= t; i++) {
          list.setValue(i - f, new nodeSass.types.String('h' + i));
        }

        return list;
      }
    }
  }).css.toString()
);

// Will gives you:
// h2, h3, h4, h5 { color: #08c; }