refactor(example/basic): Add documentation to examples, use wrapper func

example/basic/src/api/bridge.go

@@ -0,0 +1,79 @@
+package main
+
+import "syscall/js"
+
+var (
+	// bridgeName is the namesace for all functions and values set.
+	//
+	// The returning JavaScript proxy via the webpack loader will look for functions and values under this namespace.
+	bridgeName = "__go_wasm__"
+
+	// The JS object of the __go_wasm__ value.
+	bridge js.Value
+
+	// Wrapper is a simple JS function that when called with a Go Function, will return a new function that will throw
+	// if the property `error` is an instance of JavaScript's `error`.
+	//
+	// All Go functions in the bridgeName proxy are  expected to be the result of calling wrapper with the Go function.
+	wrapper js.Value
+)
+
+// newReturnValue creates an object with the value as the result.
+// See wrapGoFunc for the reasoning behind style style of returning values from Go functions.
+func newReturnValue(value interface{}) js.Value {
+	jsObject := js.Global().Get("Object").New()
+	jsObject.Set("result", value)
+
+	return jsObject
+}
+
+// newReturnError creates an object with the goError's message and creates a Javascript Error object with the message.
+//
+// See wrapGoFunc for the reasoning behind style style of returning values from Go functions.
+func newReturnError(goErr error) js.Value {
+	jsObject := js.Global().Get("Object").New()
+	jsError := js.Global().Get("Error")
+	jsObject.Set("error", jsError.New(goErr.Error()))
+
+	return jsObject
+}
+
+// Using this wrapper makes it possible to throw errors in go-fashion.
+// This means that all wrapped functions must return error and a value.
+//
+// The __wrapper__ function from JS will automatically throw if the returned object has an 'error' property.
+// Inversly, it will automatically give the result value if that property exists.
+// All go functions directly returned via wasm should keep this in mind.
+func wrapGoFunc(f func(js.Value, []js.Value) (interface{}, error)) js.Func {
+	return js.FuncOf(func(this js.Value, args []js.Value) interface{} {
+		res, err := f(this, args)
+		if err != nil {
+			return newReturnError(err)
+		}
+
+		return newReturnValue(res)
+	})
+}
+
+func setFunc(name string, f func(js.Value, []js.Value) (interface{}, error)) {
+	bridge.Set(name, wrapper.Invoke(wrapGoFunc(f)))
+}
+
+func setValue(name string, value interface{}) {
+	bridge.Set(name, value)
+}
+
+// Toggling the __ready__ value in the bridge lets JS know that everything is setup.
+// Setting __ready__ to true can help prevent possible race conditions of Wasm being called before everything is
+// registered, and potentially crashing applications.
+func ready() {
+	bridge.Set("__ready__", true)
+	<-make(chan bool, 0) // To use anything from Go WASM, the program may not exit.
+}
+
+// We want to make sure that this is always ran first. This means that we can make sure that whenever functions are
+// initialized, they are able to be set to the bridge and wrapper.
+func init() {
+	bridge = js.Global().Get(bridgeName)
+	wrapper = bridge.Get("__wrapper__")
+}

example/basic/src/api/main.go

@@ -5,27 +5,24 @@ import (
 	"syscall/js"
 )
 
-func main() {
-	fmt.Println("Hello from go-mod-wasm!")
-	setup()
-
-	c := make(chan bool, 0) // To use anything from Go WASM, the program may not exit.
-	<-c
-}
-
-const hello = "Sample value"
-
-func helloName(_ js.Value, args []js.Value) interface{} {
-	return fmt.Sprintf("Hello, %s!", args[0].String())
+const hello = "Hello!"
+
+// helloName's first value is JavaScript's `this`.
+// However, the way that the JS bridge is written, it will always be JavaScript's undefined.
+//
+// If returning a non-nil error value, the resulting promise will be rejected by API consumers.
+// The rejected value will JavaScript's Error, with the message being the go error's message.
+//
+// See other examples which use the Go wasm bridge api, which show more flexibility and type safety when interacting
+// with JavaScript.
+func helloName(_ js.Value, args []js.Value) (interface{}, error) {
+	return fmt.Sprintf("Hello, %s!", args[0].String()), nil
 }
 
-func setup() {
-	bridge := js.Global().Get("__go_wasm__")
-
-	bridge.Set("__ready__", true)
-
-	bridge.Set("hello", hello)
-	bridge.Set("helloName", js.FuncOf(helloName))
+func main() {
+	fmt.Println("go-mod-wasm initialized")
 
-	js.Global()
+	setFunc("helloName", helloName)
+	setValue("hello", hello)
+	ready()
 }