JavaScript Templating HTML With Template Strings


Example

You can create an HTML`...` template string tag function to automatically encodes interpolated values. (This requires that interpolated values are only used as text, and may not be safe if interpolated values are used in code such as scripts or styles.)

class HTMLString extends String {
  static escape(text) {
    if (text instanceof HTMLString) {
      return text;
    }
    return new HTMLString(
        String(text)
            .replace(/&/g, '&')
            .replace(/</g, '&lt;')
            .replace(/>/g, '&gt;')
            .replace(/"/g, '&quot;')
            .replace(/\\/g, '&#39;'));
  }
}

function HTML(strings, ...substitutions) { 
  const escapedFlattenedSubstitutions =
      substitutions.map(s => [].concat(s).map(HTMLString.escape).join(''));
  const pieces = [];
  for (const i of strings.keys()) {
    pieces.push(strings[i], escapedFlattenedSubstitutions [i] || '');
  }
  return new HTMLString(pieces.join(''));
}

const title = "Hello World";
const iconSrc = "/images/logo.png";
const names = ["John", "Jane", "Joe", "Jill"];

document.body.innerHTML = HTML`
  <h1><img src="${iconSrc}" /> ${title}</h1>

  <ul> ${names.map(name => HTML`
    <li>${name}</li>
  `)} </ul>
`;