helpers

bridge.go

@@ -2,7 +2,9 @@ package wasm
 
 import (
 	"context"
+	"crypto/rand"
 	"encoding/binary"
+	"errors"
 	"fmt"
 	"log"
 	"math"
@@ -129,6 +131,12 @@ func (b *Bridge) addValues() {
 						}),
 					}}
 				}},
+				"crypto": propObject("crypto", map[string]interface{}{
+					"getRandomValues": Func(func(args []interface{}) (interface{}, error) {
+						arr := args[0].(*array)
+						return rand.Read(arr.data())
+					}),
+				}),
 				"fs": propObject("fs", map[string]interface{}{
 					"constants": propObject("constants", map[string]interface{}{
 						"O_WRONLY": syscall.O_WRONLY,
@@ -440,7 +448,7 @@ func (b *Bridge) makeFuncWrapper(id, this interface{}, args *[]interface{}) (int
 	b.valuesMu.RUnlock()
 	event := propObject("_pendingEvent", map[string]interface{}{
 		"id":   id,
-		"this": nil,
+		"this": goObj,
 		"args": args,
 	})
 
@@ -473,3 +481,21 @@ func (b *Bridge) SetFunc(fname string, fn Func) error {
 	b.values[5].(*object).props[fname] = &fn
 	return nil
 }
+
+func Bytes(v interface{}) ([]byte, error) {
+	arr, ok := v.(*array)
+	if !ok {
+		return nil, fmt.Errorf("got %T instead of bytes", v)
+	}
+
+	return arr.data(), nil
+}
+
+func Error(v interface{}) (errVal error, err error) {
+	str, ok := v.(string)
+	if !ok {
+		return nil, fmt.Errorf("got %T instead of error", v)
+	}
+
+	return errors.New(str), nil
+}

examples/caller/main.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"context"
+	"fmt"
 	"log"
 
 	"github.com/vedhavyas/go-wasm"
@@ -48,4 +49,27 @@ func main() {
 		panic(err)
 	}
 	log.Printf("Multiplier: %v\n", mul)
+
+	res, err := b.CallFunc("getBytes", nil)
+	if err != nil {
+		panic(err)
+	}
+
+	bytes, err := wasm.Bytes(res)
+	if err != nil {
+		panic(err)
+	}
+	fmt.Println(bytes)
+
+	res, err = b.CallFunc("getError", nil)
+	if err != nil {
+		panic(err)
+	}
+
+	verr, err := wasm.Error(res)
+	if err != nil {
+		panic(err)
+	}
+
+	fmt.Println(verr)
 }

examples/wasm/main.go

@@ -3,6 +3,8 @@
 package main
 
 import (
+	"crypto/rand"
+	"errors"
 	"log"
 	"syscall/js"
 )
@@ -17,12 +19,28 @@ func multiplier(this js.Value, args []js.Value) interface{} {
 	return 10
 }
 
+func getBytes(this js.Value, args []js.Value) interface{} {
+	r := make([]byte, 32)
+	_, err := rand.Read(r)
+	if err != nil {
+		panic(err)
+	}
+	return js.TypedArrayOf(r)
+}
+
+func getError(this js.Value, args []js.Value) interface{} {
+	err := errors.New("test errors")
+	return err.Error()
+}
+
 func main() {
 	ch := make(chan bool)
 
 	// register functions
 	js.Global().Set("addition", js.FuncOf(addition))
 	js.Global().Set("multiplier", js.FuncOf(multiplier))
+	js.Global().Set("getBytes", js.FuncOf(getBytes))
+	js.Global().Set("getError", js.FuncOf(getError))
 
 	res := js.Global().Get("addProxy").Invoke(1, 2)
 	log.Printf("1 + 2 = %d\n", res.Int())