Export an `init` function

In order to allow pre-emptive initialisation of the wasm module to prevent an unwanted lag on the first request.

Current workaround is calling new HtmlRewriter() and a delay() function, but this functionality should ideally be exported from the library.

A better workaround for the time being:

// execute at start of module
const res = new HTMLRewriter().transform(new Response("Initialized wasm"));
console.log(await res.text());

[qwtel]

new HTMLRewriter() should be all that is required to trigger WASM initialization.

The code this module is based on triggered the WASM initialization lazily as part of transform, but I moved it inside the constructor as I thought it was more appropriate for a polyfill.

What I mean to say is there is a delay the first time you use it while it is loading the wasm. It would be good if you could load the wasm when your module starts (when using this in deno for example) to avoid the delay on first usage.

[qwtel]

Can you confirm that calling new HTMLRewriter() (without transform etc.) at the start of the module is not enough to trigger WASM load/initialisation?

It works but feels hacky/like a workaround. A more explicit function would be preferable

Edit: Only calling the constructor is enough to trigger it but it is not possible to await the initialisation which defeats the point.