templating engine

render.ts

function render(template: string, data: any, brackets = ['{{', '}}']) {
  const output: string[] = [];

  const [left, right] =
    brackets.length > 1 ? brackets : [...brackets, ...brackets];

  let pos = 0;
  while (pos < template.length) {
    const start = template.indexOf(left, pos);
    if (start < 0) break;
    const end = template.indexOf(right, pos);
    if (end < 0) throw new Error(`expected closing bracket: '${right}'`);

    output.push(template.slice(pos, start));

    const code = 'return ' + template.slice(start + left.length, end).trim();
    const fn = new Function('', code).bind(data);
    output.push(fn());

    pos = end + right.length;
  }

  output.push(template.slice(pos, template.length));

  return output.join('');
}

render('{{ this.username.toUpperCase() }}', {
  username: 'samkcarlile',
});