Experimental conditional tagged templates for generating HTML strings

I had the idea that something like this:

function renderLocalHTML(text: string, secondary: string) {
  return html`<html>
    <head>
      <title></title>
      <meta charset="UTF-8" />
    </head>
    <body>
      <p>Test text</p>
      ${IF(secondary)}
      <p>${trusted(secondary)}</p>
      ${ELSEIF(text)}
      <p>${text}</p>
      ${ELSE()}
      <p>Otherwise</p>
      ${END()}
      <svg xmlns="http://www.w3.org/2000/svg">
        <rect
          stroke="black"
          fill="blue"
          x="45px"
          y="45px"
          width="200px"
          height="100px"
          stroke-width="2"
        />
      </svg>
    </body>
  </html>`;
}

Would be more readable than:

function renderLocalHTML(text: string, secondary: string) {
  return html`<html>
    <head>
      <title></title>
      <meta charset="UTF-8" />
    </head>
    <body>
      <p>Test text</p>
      ${secondary
        ? html`<p>${trusted(secondary)}</p>`
        : text
        ? html`<p>${text}</p>`
        : html`<p>Otherwise</p>`}
      <svg xmlns="http://www.w3.org/2000/svg">
        <rect
          stroke="black"
          fill="blue"
          x="45px"
          y="45px"
          width="200px"
          height="100px"
          stroke-width="2"
        />
      </svg>
    </body>
  </html>`;
}

IF, ELSEIF, ELSE, and END are used to set up conditional blocks
trusted is used to inject safe HTML strings that don't need escaping
html otherwise auto-escapes strings using the excellent html-sloppy-escaper
deno test runs the tests
deno task bench runs the benchmark

It's an experiment, not a project, so don't go expecting this to be published and maintained in any sort of way. I did include tests with full coverage and a naive benchmarking suite comparing it with other tagged templates and JSX approaches. It's roughly as fast as other tagged template and string template approaches and 4-40x faster than server-side JSX libraries.

Conditional tagged templates:

1.13x slower than Eta template

1.07x slower than Tagged templates uhtml sync

1.09x faster than Tagged templates basic html sync

4.94x faster than JSX direct to string sync

17.71x faster than Preact async

42.98x faster than JSX indirect async

If you like this, feel free to copy it into your own projects (remember to include the tests) and reuse.

baldurbjarnason/conditional-tagged-templates

Experimental conditional tagged templates for generating HTML strings