wasm Go library support

This library contains support for running Go programs under Web Assembly.

It consists of a window/DOM interface object, and simple compositor functions used for building dynamic HTML. One of the goals is to be usable with tinygo, which does not support the full range of Go's standard library.

Examples are available to show how the library can be used.

Window

Window is a simple interface to the browser DOM, allowing callbacks to be added for keyboard shortcuts, window resizing, swipe gestures:

	w := wasm.Window()
	w.OnSwipe(func (d wasm.Direction) bool {
		if d == wasm.Right {
			...
			return true // Right swipe is handled
		}
		return false // Not interested in other swipes, use default action
	})
	w.OnResize(resized)
	w.SetTitle("My window")
	w.Wait()

Compositor

The compositor allows HTML pages or fragments to be generated in a easy and consistent flow of functions. Tags are automatically closed where required, and common attributes are supported. For example:

import (
	"github.com/aamcrae/wasm"
)
...
	w := wasm.Window()
	h := wasm.NewHTML()
	h.Wr(h.H1("Title Page"))
	h.Wr(h.A(h.Href("page/index.html"), h.Id("myid"), h.Img(h.Class("image"), h.Src("flower.jpg"), h.Alt("Flower"))))
	h.Wr(h.Span(h.Class("myspan"), h.Open()) // Don't close tag
	h.Wr(h.P("This is a paragraph", h.Br(), "with a break in it)))
	h.Wr(h.Text("Combining numbers ", 12345, ", runes ", ' ', rune(0x21A7), " and strings"))
	h.Wr(h.Span(h.Close())) // Now add the closing tag for span
	w.Display(h.String())

Modifiers and conditionals are allowed so that the flow can be maintained when deeply embedded functions are used (without resorting to if/else control flow):

	// Only display title if it is not empty
	h.Wr(h.H1(h.If(len(title) > 0), title))
	h.Wr(h.A(h.Open(), h.Id("id", i), h.Href("#")))
	// complicated code to generate anchor
	h.Wr(h.A(h.Close()))

Be aware that complete syntax checking is not performed by the compositor e.g there is nothing stopping incorrect attributes being used in tags, or tags not being closed etc.

Fetcher

Fetcher is an interface to the Javascript fetch API. This interface is usable with tinygo (which does not support net/http). It allows concurrent fetching of resources:

	// Start fetching all the files required
	f1 := w.Fetcher("data/file1")
	f2 := w.Fetcher("data/file2")
	f3 := w.Fetcher("data/file3")
	...
	go func() {
		val, err := f3.Get() // Blocks until file3 is read.
		...
	}
	// Retrieve data only when available
	if f1.Ready() {
		data1, err := f1.Get()
		...
	}
	data2, err := f2.Get() // blocks until ready