Merge pull request #1180 from visualfc/emcc_js

[WIP] runtime/js: js for emscripten

runtime/js/embind/_wrap/emval.cpp

@@ -0,0 +1,213 @@
+#include <string>
+#include <emscripten.h>
+#include <emscripten/val.h>
+#include <emscripten/bind.h>
+
+using namespace emscripten;
+using namespace emscripten::internal;
+
+template<typename T>
+TYPEID take_typeid() {
+    typename WithPolicies<>::template ArgTypeList<T> targetType;
+    return targetType.getTypes()[0];    
+}
+
+template<typename T, typename... Policies>
+EM_VAL take_value(T&& value, Policies...) {
+    typename WithPolicies<Policies...>::template ArgTypeList<T> valueType;
+    WireTypePack<T> argv(std::forward<T>(value));
+    return _emval_take_value(valueType.getTypes()[0], argv);
+}
+
+template<typename T, typename ...Policies>
+T as_value(EM_VAL val, Policies...) {
+    typedef BindingType<T> BT;
+    typename WithPolicies<Policies...>::template ArgTypeList<T> targetType;
+    
+    EM_DESTRUCTORS destructors = nullptr;
+    EM_GENERIC_WIRE_TYPE result = _emval_as(
+        val,
+        targetType.getTypes()[0],
+        &destructors);
+    DestructorsRunner dr(destructors);
+    return fromGenericWireType<T>(result);
+}
+
+struct GoString {
+    char *data;
+    int len;   
+};
+
+static TYPEID typeid_val = take_typeid<val>();
+
+extern "C" {
+
+// export from llgo
+extern GoString llgo_export_string_from(const char *data, int n);
+extern bool llgo_export_invoke(EM_VAL args);
+
+EM_VAL llgo_emval_get_global(const char *name) {
+    return _emval_get_global(name);
+}
+
+EM_VAL llgo_emval_new_double(double v) {
+    return take_value(v);
+}
+
+EM_VAL llgo_emval_new_string(const char *str) {
+    return _emval_new_u8string(str);
+}
+
+EM_VAL llgo_emval_new_object() {
+    return _emval_new_object();
+}
+
+EM_VAL llgo_emval_new_array() {
+    return _emval_new_array();
+}
+
+void llgo_emval_incref(EM_VAL value) {
+    _emval_incref(value);
+}
+
+void llgo_emval_decref(EM_VAL value) {
+    _emval_decref(value);
+}
+
+void llgo_emval_set_property(EM_VAL object, EM_VAL key, EM_VAL value) {
+    _emval_set_property(object, key, value);
+}
+
+EM_VAL llgo_emval_get_property(EM_VAL object, EM_VAL key) {
+    return _emval_get_property(object, key);
+}
+
+bool llgo_emval_is_number(EM_VAL object) {
+    return _emval_is_number(object);
+}
+
+bool llgo_emval_is_string(EM_VAL object) {
+    return _emval_is_string(object);
+}
+
+bool llgo_emval_in(EM_VAL item, EM_VAL object) {
+    return _emval_in(item, object);
+}
+
+bool llgo_emval_delete(EM_VAL object, EM_VAL property) {
+    return _emval_delete(object, property);
+}
+
+EM_VAL llgo_emval_typeof(EM_VAL value) {
+    return _emval_typeof(value);
+}
+
+bool llgo_emval_instanceof(EM_VAL object, EM_VAL constructor) {
+    return _emval_instanceof(object, constructor);
+}
+
+double llgo_emval_as_double(EM_VAL v) {
+    return as_value<double>(v);
+}
+
+GoString llgo_emval_as_string(EM_VAL v) {
+    std::string value = as_value<std::string>(v);
+    return llgo_export_string_from(value.c_str(), int(value.size()));
+}
+
+bool llgo_emval_equals(EM_VAL first, EM_VAL second) {
+    return _emval_equals(first, second);
+}
+
+EM_VAL llgo_emval_method_call(EM_VAL object, const char* name, EM_VAL args[], int nargs, int *error) {
+    std::vector<TYPEID> arr;
+    arr.resize(nargs+1);
+    std::vector<val> _args;
+    _args.resize(nargs);
+    std::vector<GenericWireType> elements;
+    elements.resize(nargs);
+    GenericWireType *cursor = elements.data();
+    arr[0] = typeid_val;
+    for (int i = 0; i < nargs; i++) {
+        arr[i+1] = typeid_val;
+        val v = val::take_ownership(args[i]);
+        _args[i] = v;
+        writeGenericWireTypes(cursor, v); 
+    }
+    EM_METHOD_CALLER caller = _emval_get_method_caller(nargs+1,&arr[0],EM_METHOD_CALLER_KIND::FUNCTION);
+    EM_GENERIC_WIRE_TYPE ret;
+    try {
+        EM_DESTRUCTORS destructors = nullptr;
+        ret = _emval_call_method(caller, object, name, &destructors, elements.data());        
+    } catch(const emscripten::val& jsErr) {
+        printf("error\n");
+        *error = 1; 
+        return EM_VAL(internal::_EMVAL_UNDEFINED);
+    }
+    return fromGenericWireType<val>(ret).release_ownership();   
+}
+
+/*
+kind:
+FUNCTION = 0,
+CONSTRUCTOR = 1,
+*/
+EM_VAL llgo_emval_call(EM_VAL fn, EM_VAL args[], int nargs, int kind, int *error) {
+    std::vector<TYPEID> arr;
+    arr.resize(nargs+1);
+    std::vector<val> _args;
+    _args.resize(nargs);
+    std::vector<GenericWireType> elements;
+    elements.resize(nargs);
+    GenericWireType *cursor = elements.data();
+    arr[0] = typeid_val;
+    for (int i = 0; i < nargs; i++) {
+        arr[i+1] = typeid_val;
+        val v = val::take_ownership(args[i]);
+        _args[i] = v;
+        writeGenericWireTypes(cursor, v); 
+    }
+    EM_METHOD_CALLER caller = _emval_get_method_caller(nargs+1,&arr[0],EM_METHOD_CALLER_KIND(kind));
+    EM_GENERIC_WIRE_TYPE ret;
+    try {
+        EM_DESTRUCTORS destructors = nullptr;
+        ret = _emval_call(caller, fn, &destructors, elements.data());
+    } catch(const emscripten::val& jsErr) {
+       *error = 1; 
+        return EM_VAL(internal::_EMVAL_UNDEFINED);
+    }
+    return fromGenericWireType<val>(ret).release_ownership();
+}
+
+/*
+TYPEID llgo_emval_typeid_void() {
+    return take_typeid<void>();
+}
+
+TYPEID llgo_emval_typeid_double() {
+    return take_typeid<double>();
+}
+
+TYPEID llgo_emval_typeid_string() {
+    return take_typeid<std::string>();
+}
+
+TYPEID llgo_emval_typeid_val() {
+    return take_typeid<val>();
+}
+*/
+
+void llgo_emval_dump(EM_VAL v) {
+    val console = val::global("console");
+    console.call<void>("log", val::take_ownership(v));
+}
+
+}
+
+bool invoke(val args) {
+    return llgo_export_invoke(args.as_handle());
+}
+
+EMSCRIPTEN_BINDINGS(my_module) {
+    function("_llgo_invoke", &invoke);
+}

runtime/js/embind/embind.go

@@ -0,0 +1,6 @@
+package embind
+
+const (
+	LLGoFiles   = "_wrap/emval.cpp"
+	LLGoPackage = "link: -lembind"
+)

runtime/js/emval.go

@@ -0,0 +1,92 @@
+//go:build js && wasm
+// +build js,wasm
+
+package js
+
+import (
+	_ "unsafe"
+
+	c "github.com/goplus/llgo/runtime/internal/clite"
+	_ "github.com/goplus/llgo/runtime/js/embind"
+)
+
+var (
+	valueGlobal         = emval_get_global(nil)
+	objectConstructor   = emval_get_global(c.Str("Object"))
+	stringConstructor   = emval_get_global(c.Str("String"))
+	arrayConstructor    = emval_get_global(c.Str("Array"))
+	functionConstructor = emval_get_global(c.Str("Function"))
+)
+
+var (
+	valueUndefined = Value{2}
+	valueNull      = Value{4}
+	valueTrue      = Value{6}
+	valueFalse     = Value{8}
+	valueNaN       = emval_get_global(c.Str("NaN"))
+	valueZero      = emval_new_double(0)
+)
+
+//go:linkname emval_get_global C.llgo_emval_get_global
+func emval_get_global(name *c.Char) Value
+
+//go:linkname emval_new_double C.llgo_emval_new_double
+func emval_new_double(v float64) Value
+
+//go:linkname emval_new_string C.llgo_emval_new_string
+func emval_new_string(str *c.Char) Value
+
+//go:linkname emval_new_object C.llgo_emval_new_object
+func emval_new_object() Value
+
+//go:linkname emval_new_array C.llgo_emval_new_array
+func emval_new_array() Value
+
+//go:linkname emval_set_property C.llgo_emval_set_property
+func emval_set_property(object Value, key Value, value Value)
+
+//go:linkname emval_get_property C.llgo_emval_get_property
+func emval_get_property(object Value, key Value) Value
+
+//go:linkname emval_delete C.llgo_emval_delete
+func emval_delete(object Value, property Value) bool
+
+//go:linkname emval_is_number C.llgo_emval_is_number
+func emval_is_number(object Value) bool
+
+//go:linkname emval_is_string C.llgo_emval_is_string
+func emval_is_string(object Value) bool
+
+//go:linkname emval_in C.llgo_emval_in
+func emval_in(item Value, object Value) bool
+
+//go:linkname emval_typeof C.llgo_emval_typeof
+func emval_typeof(value Value) Value
+
+//go:linkname emval_instanceof C.llgo_emval_instanceof
+func emval_instanceof(object Value, constructor Value) bool
+
+//go:linkname emval_as_double C.llgo_emval_as_double
+func emval_as_double(v Value) float64
+
+//go:linkname emval_as_string C.llgo_emval_as_string
+func emval_as_string(v Value) string
+
+//go:linkname emval_equals C.llgo_emval_equals
+func emval_equals(first Value, second Value) bool
+
+//go:linkname emval_method_call C.llgo_emval_method_call
+func emval_method_call(object Value, name *c.Char, args *Value, nargs c.Int, err *c.Int) Value
+
+// emval_call kind: FUNCTION = 0, CONSTRUCTOR = 1
+//
+//go:linkname emval_call C.llgo_emval_call
+func emval_call(fn Value, args *Value, nargs c.Int, kind c.Int, err *c.Int) Value
+
+//go:linkname emval_dump C.llgo_emval_dump
+func emval_dump(v Value)
+
+//export llgo_export_string_from
+func llgo_export_string_from(data *c.Char, size c.Int) string {
+	return c.GoString(data, size)
+}

runtime/js/func.go

@@ -0,0 +1,95 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build js && wasm
+// +build js,wasm
+
+package js
+
+import (
+	"strconv"
+	"sync"
+)
+
+var (
+	funcsMu    sync.Mutex
+	funcs             = make(map[uint32]func(Value, []Value) any)
+	nextFuncID uint32 = 1
+)
+
+// Func is a wrapped Go function to be called by JavaScript.
+type Func struct {
+	Value // the JavaScript function that invokes the Go function
+	id    uint32
+}
+
+// FuncOf returns a function to be used by JavaScript.
+//
+// The Go function fn is called with the value of JavaScript's "this" keyword and the
+// arguments of the invocation. The return value of the invocation is
+// the result of the Go function mapped back to JavaScript according to ValueOf.
+//
+// Invoking the wrapped Go function from JavaScript will
+// pause the event loop and spawn a new goroutine.
+// Other wrapped functions which are triggered during a call from Go to JavaScript
+// get executed on the same goroutine.
+//
+// As a consequence, if one wrapped function blocks, JavaScript's event loop
+// is blocked until that function returns. Hence, calling any async JavaScript
+// API, which requires the event loop, like fetch (http.Client), will cause an
+// immediate deadlock. Therefore a blocking function should explicitly start a
+// new goroutine.
+//
+// Func.Release must be called to free up resources when the function will not be invoked any more.
+func FuncOf(fn func(this Value, args []Value) any) Func {
+	funcsMu.Lock()
+	id := nextFuncID
+	nextFuncID++
+	funcs[id] = fn
+	funcsMu.Unlock()
+	sid := strconv.Itoa(int(id))
+	wrap := functionConstructor.New(ValueOf(`
+		const event = { id:` + sid + `, this: this, args: arguments };
+		Module._llgo_invoke(event);
+		return event.result;
+	`))
+	return Func{
+		id:    id,
+		Value: wrap,
+	}
+}
+
+// Release frees up resources allocated for the function.
+// The function must not be invoked after calling Release.
+// It is allowed to call Release while the function is still running.
+func (c Func) Release() {
+	funcsMu.Lock()
+	delete(funcs, c.id)
+	funcsMu.Unlock()
+}
+
+//export llgo_export_invoke
+func llgo_export_invoke(cb Value) bool {
+	id := uint32(cb.Get("id").Int())
+	funcsMu.Lock()
+	f, ok := funcs[id]
+	funcsMu.Unlock()
+	if !ok {
+		Global().Get("console").Call("error", "call to released function")
+		return true
+	}
+
+	// Call the js.Func with arguments
+	this := cb.Get("this")
+	argsObj := cb.Get("args")
+	args := make([]Value, argsObj.Length())
+	for i := range args {
+		args[i] = argsObj.Index(i)
+	}
+	result := f(this, args)
+
+	// Return the result to js
+	cb.Set("result", result)
+	return true
+}

runtime/js/js.go

@@ -0,0 +1,707 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build js && wasm
+// +build js,wasm
+
+// Package js gives access to the WebAssembly host environment when using the js/wasm architecture.
+// Its API is based on JavaScript semantics.
+//
+// This package is EXPERIMENTAL. Its current scope is only to allow tests to run, but not yet to provide a
+// comprehensive API for users. It is exempt from the Go compatibility promise.
+package js
+
+import (
+	"unsafe"
+
+	c "github.com/goplus/llgo/runtime/internal/clite"
+)
+
+// Value represents a JavaScript value. The zero value is the JavaScript value "undefined".
+// Values can be checked for equality with the Equal method.
+type Value struct {
+	ref uintptr
+}
+
+func floatValue(f float64) Value {
+	if f == 0 {
+		return valueZero
+	}
+	if f != f {
+		return valueNaN
+	}
+	return emval_new_double(f)
+}
+
+func intValue(i int) Value {
+	if i == 0 {
+		return valueZero
+	}
+	return emval_new_double(float64(i))
+}
+
+// Error wraps a JavaScript error.
+type Error struct {
+	// Value is the underlying JavaScript error value.
+	Value
+}
+
+// Error implements the error interface.
+func (e Error) Error() string {
+	return "JavaScript error: " + e.Get("message").String()
+}
+
+/*
+var (
+	valueUndefined = Value{ref: 0}
+	valueNaN       = predefValue(0, typeFlagNone)
+	valueZero      = predefValue(1, typeFlagNone)
+	valueNull      = predefValue(2, typeFlagNone)
+	valueTrue      = predefValue(3, typeFlagNone)
+	valueFalse     = predefValue(4, typeFlagNone)
+	valueGlobal    = predefValue(5, typeFlagObject)
+	jsGo           = predefValue(6, typeFlagObject) // instance of the Go class in JavaScript
+
+	objectConstructor = valueGlobal.Get("Object")
+	arrayConstructor  = valueGlobal.Get("Array")
+)
+*/
+
+// Equal reports whether v and w are equal according to JavaScript's === operator.
+func (v Value) Equal(w Value) bool {
+	return emval_equals(v, w) && v.ref != valueNaN.ref
+}
+
+// Undefined returns the JavaScript value "undefined".
+func Undefined() Value {
+	return valueUndefined
+}
+
+// IsUndefined reports whether v is the JavaScript value "undefined".
+func (v Value) IsUndefined() bool {
+	return v.ref == valueUndefined.ref
+}
+
+// Null returns the JavaScript value "null".
+func Null() Value {
+	return valueNull
+}
+
+// IsNull reports whether v is the JavaScript value "null".
+func (v Value) IsNull() bool {
+	return v.ref == valueNull.ref
+}
+
+// IsNaN reports whether v is the JavaScript value "NaN".
+func (v Value) IsNaN() bool {
+	return v.ref == valueNaN.ref
+}
+
+// Global returns the JavaScript global object, usually "window" or "global".
+func Global() Value {
+	return valueGlobal
+}
+
+// ValueOf returns x as a JavaScript value:
+//
+//	| Go                     | JavaScript             |
+//	| ---------------------- | ---------------------- |
+//	| js.Value               | [its value]            |
+//	| js.Func                | function               |
+//	| nil                    | null                   |
+//	| bool                   | boolean                |
+//	| integers and floats    | number                 |
+//	| string                 | string                 |
+//	| []interface{}          | new array              |
+//	| map[string]interface{} | new object             |
+//
+// Panics if x is not one of the expected types.
+func ValueOf(x any) Value {
+	switch x := x.(type) {
+	case Value:
+		return x
+	case Func:
+		return x.Value
+	case nil:
+		return valueNull
+	case bool:
+		if x {
+			return valueTrue
+		} else {
+			return valueFalse
+		}
+	case int:
+		return floatValue(float64(x))
+	case int8:
+		return floatValue(float64(x))
+	case int16:
+		return floatValue(float64(x))
+	case int32:
+		return floatValue(float64(x))
+	case int64:
+		return floatValue(float64(x))
+	case uint:
+		return floatValue(float64(x))
+	case uint8:
+		return floatValue(float64(x))
+	case uint16:
+		return floatValue(float64(x))
+	case uint32:
+		return floatValue(float64(x))
+	case uint64:
+		return floatValue(float64(x))
+	case uintptr:
+		return floatValue(float64(x))
+	case unsafe.Pointer:
+		return floatValue(float64(uintptr(x)))
+	case float32:
+		return floatValue(float64(x))
+	case float64:
+		return floatValue(x)
+	case string:
+		return stringVal(x)
+	case []any:
+		a := arrayConstructor.New(len(x))
+		for i, s := range x {
+			a.SetIndex(i, s)
+		}
+		return a
+	case map[string]any:
+		o := objectConstructor.New()
+		for k, v := range x {
+			o.Set(k, v)
+		}
+		return o
+	default:
+		panic("ValueOf: invalid value")
+	}
+}
+
+func stringVal(x string) Value {
+	return emval_new_string(c.AllocaCStr(x))
+}
+
+// Type represents the JavaScript type of a Value.
+type Type int
+
+const (
+	TypeUndefined Type = iota
+	TypeNull
+	TypeBoolean
+	TypeNumber
+	TypeString
+	TypeSymbol
+	TypeObject
+	TypeFunction
+)
+
+func (t Type) String() string {
+	switch t {
+	case TypeUndefined:
+		return "undefined"
+	case TypeNull:
+		return "null"
+	case TypeBoolean:
+		return "boolean"
+	case TypeNumber:
+		return "number"
+	case TypeString:
+		return "string"
+	case TypeSymbol:
+		return "symbol"
+	case TypeObject:
+		return "object"
+	case TypeFunction:
+		return "function"
+	default:
+		panic("bad type")
+	}
+}
+
+func (t Type) isObject() bool {
+	return t == TypeObject || t == TypeFunction
+}
+
+// Type returns the JavaScript type of the value v. It is similar to JavaScript's typeof operator,
+// except that it returns TypeNull instead of TypeObject for null.
+func (v Value) Type() Type {
+	switch v.ref {
+	case valueUndefined.ref:
+		return TypeUndefined
+	case valueNull.ref:
+		return TypeNull
+	case valueTrue.ref, valueFalse.ref:
+		return TypeBoolean
+	}
+	if emval_is_number(v) {
+		return TypeNumber
+	} else if emval_is_string(v) {
+		return TypeString
+	}
+	switch emval_as_string(emval_typeof(v)) {
+	case "object":
+		return TypeObject
+	case "symbol":
+		return TypeSymbol
+	case "function":
+		return TypeFunction
+	default:
+		panic("bad type")
+	}
+}
+
+// Get returns the JavaScript property p of value v.
+// It panics if v is not a JavaScript object.
+func (v Value) Get(p string) Value {
+	if vType := v.Type(); !vType.isObject() {
+		panic(&ValueError{"Value.Get", vType})
+	}
+	return emval_get_property(v, stringVal(p))
+	// r := makeValue(valueGet(v.ref, p))
+	// runtime.KeepAlive(v)
+	// return r
+}
+
+// Set sets the JavaScript property p of value v to ValueOf(x).
+// It panics if v is not a JavaScript object.
+func (v Value) Set(p string, x any) {
+	if vType := v.Type(); !vType.isObject() {
+		panic(&ValueError{"Value.Set", vType})
+	}
+	// xv := ValueOf(x)
+	emval_set_property(v, stringVal(p), ValueOf(x))
+	// valueSet(v.ref, p, xv.ref)
+	// runtime.KeepAlive(v)
+	// runtime.KeepAlive(xv)
+}
+
+// // valueSet sets property p of ref v to ref x.
+// //
+// // Using go:noescape is safe because no references are maintained to the
+// // Go string p after the syscall returns.
+// //
+// //go:wasmimport gojs syscall/js.valueSet
+// //go:noescape
+// func valueSet(v ref, p string, x ref)
+
+// Delete deletes the JavaScript property p of value v.
+// It panics if v is not a JavaScript object.
+func (v Value) Delete(p string) {
+	if vType := v.Type(); !vType.isObject() {
+		panic(&ValueError{"Value.Delete", vType})
+	}
+	emval_delete(v, ValueOf(p))
+	//valueDelete(v.ref, p)
+	//runtime.KeepAlive(v)
+}
+
+// // valueDelete deletes the JavaScript property p of ref v.
+// //
+// // Using go:noescape is safe because no references are maintained to the
+// // Go string p after the syscall returns.
+// //
+// //go:wasmimport gojs syscall/js.valueDelete
+// //go:noescape
+// func valueDelete(v ref, p string)
+
+// Index returns JavaScript index i of value v.
+// It panics if v is not a JavaScript object.
+func (v Value) Index(i int) Value {
+	if vType := v.Type(); !vType.isObject() {
+		panic(&ValueError{"Value.Index", vType})
+	}
+	return emval_get_property(v, intValue(i))
+	// r := makeValue(valueIndex(v.ref, i))
+	// runtime.KeepAlive(v)
+	// return r
+}
+
+// //go:wasmimport gojs syscall/js.valueIndex
+// func valueIndex(v ref, i int) ref
+
+// SetIndex sets the JavaScript index i of value v to ValueOf(x).
+// It panics if v is not a JavaScript object.
+func (v Value) SetIndex(i int, x any) {
+	if vType := v.Type(); !vType.isObject() {
+		panic(&ValueError{"Value.SetIndex", vType})
+	}
+	emval_set_property(v, intValue(i), ValueOf(x))
+	// xv := ValueOf(x)
+	// valueSetIndex(v.ref, i, xv.ref)
+	// runtime.KeepAlive(v)
+	// runtime.KeepAlive(xv)
+}
+
+// //go:wasmimport gojs syscall/js.valueSetIndex
+// func valueSetIndex(v ref, i int, x ref)
+
+// makeArgSlices makes two slices to hold JavaScript arg data.
+// It can be paired with storeArgs to make-and-store JavaScript arg slices.
+// However, the two functions are separated to ensure makeArgSlices is inlined
+// which will prevent the slices from being heap allocated for small (<=16)
+// numbers of args.
+// func makeArgSlices(size int) (argVals []Value, argRefs []ref) {
+// 	// value chosen for being power of two, and enough to handle all web APIs
+// 	// in particular, note that WebGL2's texImage2D takes up to 10 arguments
+// 	const maxStackArgs = 16
+// 	if size <= maxStackArgs {
+// 		// as long as makeArgs is inlined, these will be stack-allocated
+// 		argVals = make([]Value, size, maxStackArgs)
+// 		argRefs = make([]ref, size, maxStackArgs)
+// 	} else {
+// 		// allocates on the heap, but exceeding maxStackArgs should be rare
+// 		argVals = make([]Value, size)
+// 		argRefs = make([]ref, size)
+// 	}
+// 	return
+// }
+
+// storeArgs maps input args onto respective Value and ref slices.
+// It can be paired with makeArgSlices to make-and-store JavaScript arg slices.
+// func storeArgs(args []any, argValsDst []Value, argRefsDst []ref) {
+// 	// would go in makeArgs if the combined func was simple enough to inline
+// 	for i, arg := range args {
+// 		v := ValueOf(arg)
+// 		argValsDst[i] = v
+// 		argRefsDst[i] = v.ref
+// 	}
+// }
+
+// Length returns the JavaScript property "length" of v.
+// It panics if v is not a JavaScript object.
+func (v Value) Length() int {
+	if vType := v.Type(); !vType.isObject() {
+		panic(&ValueError{"Value.SetIndex", vType})
+	}
+	return emval_get_property(v, emval_new_string(c.Str("length"))).Int()
+	//r := valueLength(v.ref)
+	//runtime.KeepAlive(v)
+	//return r
+}
+
+// //go:wasmimport gojs syscall/js.valueLength
+// func valueLength(v ref) int
+
+// Call does a JavaScript call to the method m of value v with the given arguments.
+// It panics if v has no method m.
+// The arguments get mapped to JavaScript values according to the ValueOf function.
+func (v Value) Call(m string, args ...any) (res Value) {
+	var err c.Int
+	if len(args) == 0 {
+		res = emval_method_call(v, c.AllocaCStr(m), nil, 0, &err)
+	} else {
+		vargs := make([]Value, len(args))
+		for i := 0; i < len(args); i++ {
+			vargs[i] = ValueOf(args[i])
+		}
+		res = emval_method_call(v, c.AllocaCStr(m), *(**Value)(unsafe.Pointer(&vargs)), c.Int(len(args)), &err)
+	}
+	if err != 0 {
+		if vType := v.Type(); !vType.isObject() { // check here to avoid overhead in success case
+			panic(&ValueError{"Value.Call", vType})
+		}
+		if propType := v.Get(m).Type(); propType != TypeFunction {
+			panic("syscall/js: Value.Call: property " + m + " is not a function, got " + propType.String())
+		}
+		panic(Error{res})
+	}
+	return res
+	// argVals, argRefs := makeArgSlices(len(args))
+	// storeArgs(args, argVals, argRefs)
+	// res, ok := valueCall(v.ref, m, argRefs)
+	// runtime.KeepAlive(v)
+	// runtime.KeepAlive(argVals)
+	// if !ok {
+	// 	if vType := v.Type(); !vType.isObject() { // check here to avoid overhead in success case
+	// 		panic(&ValueError{"Value.Call", vType})
+	// 	}
+	// 	if propType := v.Get(m).Type(); propType != TypeFunction {
+	// 		panic("syscall/js: Value.Call: property " + m + " is not a function, got " + propType.String())
+	// 	}
+	// 	panic(Error{makeValue(res)})
+	// }
+	// return makeValue(res)
+}
+
+// // valueCall does a JavaScript call to the method name m of ref v with the given arguments.
+// //
+// // Using go:noescape is safe because no references are maintained to the
+// // Go string m after the syscall returns. Additionally, the args slice
+// // is only used temporarily to collect the JavaScript objects for
+// // the JavaScript method invocation.
+// //
+// //go:wasmimport gojs syscall/js.valueCall
+// //go:nosplit
+// //go:noescape
+// func valueCall(v ref, m string, args []ref) (ref, bool)
+
+// Invoke does a JavaScript call of the value v with the given arguments.
+// It panics if v is not a JavaScript function.
+// The arguments get mapped to JavaScript values according to the ValueOf function.
+func (v Value) Invoke(args ...any) (res Value) {
+	var err c.Int
+	if len(args) == 0 {
+		res = emval_call(v, nil, 0, 0, &err)
+	} else {
+		vargs := make([]Value, len(args))
+		for i := 0; i < len(args); i++ {
+			vargs[i] = ValueOf(args[i])
+		}
+		res = emval_call(v, *(**Value)(unsafe.Pointer(&vargs)), c.Int(len(args)), 0, &err)
+	}
+	if err != 0 {
+		if vType := v.Type(); vType != TypeFunction { // check here to avoid overhead in success case
+			panic(&ValueError{"Value.Invoke", vType})
+		}
+		panic(Error{res})
+	}
+	return
+
+	// argVals, argRefs := makeArgSlices(len(args))
+	// storeArgs(args, argVals, argRefs)
+	// res, ok := valueInvoke(v.ref, argRefs)
+	// runtime.KeepAlive(v)
+	// runtime.KeepAlive(argVals)
+	// if !ok {
+	// 	if vType := v.Type(); vType != TypeFunction { // check here to avoid overhead in success case
+	// 		panic(&ValueError{"Value.Invoke", vType})
+	// 	}
+	// 	panic(Error{makeValue(res)})
+	// }
+	// return makeValue(res)
+}
+
+// valueInvoke does a JavaScript call to value v with the given arguments.
+//
+// Using go:noescape is safe because the args slice is only used temporarily
+// to collect the JavaScript objects for the JavaScript method
+// invocation.
+//
+// //go:wasmimport gojs syscall/js.valueInvoke
+// //go:noescape
+// func valueInvoke(v ref, args []ref) (ref, bool)
+
+// New uses JavaScript's "new" operator with value v as constructor and the given arguments.
+// It panics if v is not a JavaScript function.
+// The arguments get mapped to JavaScript values according to the ValueOf function.
+func (v Value) New(args ...any) (res Value) {
+	var err c.Int
+	if len(args) == 0 {
+		res = emval_call(v, nil, 0, 1, &err)
+	} else {
+		vargs := make([]Value, len(args))
+		for i := 0; i < len(args); i++ {
+			vargs[i] = ValueOf(args[i])
+		}
+		res = emval_call(v, *(**Value)(unsafe.Pointer(&vargs)), c.Int(len(args)), 1, &err)
+	}
+	if err != 0 {
+		if vType := v.Type(); vType != TypeFunction { // check here to avoid overhead in success case
+			panic(&ValueError{"Value.Invoke", vType})
+		}
+		panic(Error{res})
+	}
+	return
+
+	// argVals, argRefs := makeArgSlices(len(args))
+	// storeArgs(args, argVals, argRefs)
+	// res, ok := valueNew(v.ref, argRefs)
+	// runtime.KeepAlive(v)
+	// runtime.KeepAlive(argVals)
+	// if !ok {
+	// 	if vType := v.Type(); vType != TypeFunction { // check here to avoid overhead in success case
+	// 		panic(&ValueError{"Value.Invoke", vType})
+	// 	}
+	// 	panic(Error{makeValue(res)})
+	// }
+	// return makeValue(res)
+}
+
+// valueNew uses JavaScript's "new" operator with value v as a constructor and the given arguments.
+//
+// Using go:noescape is safe because the args slice is only used temporarily
+// to collect the JavaScript objects for the constructor execution.
+//
+// //go:wasmimport gojs syscall/js.valueNew
+// //go:noescape
+// func valueNew(v ref, args []ref) (ref, bool)
+
+func (v Value) isNumber() bool {
+	return v.ref == valueZero.ref ||
+		v.ref == valueNaN.ref ||
+		(v.ref != valueUndefined.ref && emval_is_number(v))
+}
+
+func (v Value) float(method string) float64 {
+	if !v.isNumber() {
+		panic(&ValueError{method, v.Type()})
+	}
+	if v.ref == valueZero.ref {
+		return 0
+	}
+	return emval_as_double(v)
+	//return *(*float64)(unsafe.Pointer(&v.ref))
+}
+
+// Float returns the value v as a float64.
+// It panics if v is not a JavaScript number.
+func (v Value) Float() float64 {
+	return v.float("Value.Float")
+}
+
+// Int returns the value v truncated to an int.
+// It panics if v is not a JavaScript number.
+func (v Value) Int() int {
+	return int(v.float("Value.Int"))
+}
+
+// Bool returns the value v as a bool.
+// It panics if v is not a JavaScript boolean.
+func (v Value) Bool() bool {
+	switch v.ref {
+	case valueTrue.ref:
+		return true
+	case valueFalse.ref:
+		return false
+	default:
+		panic(&ValueError{"Value.Bool", v.Type()})
+	}
+}
+
+// Truthy returns the JavaScript "truthiness" of the value v. In JavaScript,
+// false, 0, "", null, undefined, and NaN are "falsy", and everything else is
+// "truthy". See https://developer.mozilla.org/en-US/docs/Glossary/Truthy.
+func (v Value) Truthy() bool {
+	switch v.Type() {
+	case TypeUndefined, TypeNull:
+		return false
+	case TypeBoolean:
+		return v.Bool()
+	case TypeNumber:
+		return v.ref != valueNaN.ref && v.ref != valueZero.ref
+	case TypeString:
+		return v.String() != ""
+	case TypeSymbol, TypeFunction, TypeObject:
+		return true
+	default:
+		panic("bad type")
+	}
+}
+
+// String returns the value v as a string.
+// String is a special case because of Go's String method convention. Unlike the other getters,
+// it does not panic if v's Type is not TypeString. Instead, it returns a string of the form "<T>"
+// or "<T: V>" where T is v's type and V is a string representation of v's value.
+func (v Value) String() string {
+	switch v.Type() {
+	case TypeString:
+		return jsString(v)
+	case TypeUndefined:
+		return "<undefined>"
+	case TypeNull:
+		return "<null>"
+	case TypeBoolean:
+		return "<boolean: " + jsString(v) + ">"
+	case TypeNumber:
+		return "<number: " + jsString(v) + ">"
+	case TypeSymbol:
+		return "<symbol>"
+	case TypeObject:
+		return "<object>"
+	case TypeFunction:
+		return "<function>"
+	default:
+		panic("bad type")
+	}
+}
+
+func jsString(v Value) string {
+	return emval_as_string(v)
+	// str, length := valuePrepareString(v.ref)
+	// runtime.KeepAlive(v)
+	// b := make([]byte, length)
+	// valueLoadString(str, b)
+	// finalizeRef(str)
+	// return string(b)
+}
+
+// //go:wasmimport gojs syscall/js.valuePrepareString
+// func valuePrepareString(v ref) (ref, int)
+
+// valueLoadString loads string data located at ref v into byte slice b.
+//
+// Using go:noescape is safe because the byte slice is only used as a destination
+// for storing the string data and references to it are not maintained.
+//
+// //go:wasmimport gojs syscall/js.valueLoadString
+// //go:noescape
+// func valueLoadString(v ref, b []byte)
+
+// InstanceOf reports whether v is an instance of type t according to JavaScript's instanceof operator.
+func (v Value) InstanceOf(t Value) bool {
+	return emval_instanceof(v, t)
+	// r := valueInstanceOf(v.ref, t.ref)
+	// runtime.KeepAlive(v)
+	// runtime.KeepAlive(t)
+	// return r
+}
+
+// //go:wasmimport gojs syscall/js.valueInstanceOf
+// func valueInstanceOf(v ref, t ref) bool
+
+// A ValueError occurs when a Value method is invoked on
+// a Value that does not support it. Such cases are documented
+// in the description of each method.
+type ValueError struct {
+	Method string
+	Type   Type
+}
+
+func (e *ValueError) Error() string {
+	return "syscall/js: call of " + e.Method + " on " + e.Type.String()
+}
+
+// CopyBytesToGo copies bytes from src to dst.
+// It panics if src is not a Uint8Array or Uint8ClampedArray.
+// It returns the number of bytes copied, which will be the minimum of the lengths of src and dst.
+func CopyBytesToGo(dst []byte, src Value) int {
+	return 0
+	// n, ok := copyBytesToGo(dst, src.ref)
+	// runtime.KeepAlive(src)
+	// if !ok {
+	// 	panic("syscall/js: CopyBytesToGo: expected src to be a Uint8Array or Uint8ClampedArray")
+	// }
+	// return n
+}
+
+// copyBytesToGo copies bytes from src to dst.
+//
+// Using go:noescape is safe because the dst byte slice is only used as a dst
+// copy buffer and no references to it are maintained.
+//
+// //go:wasmimport gojs syscall/js.copyBytesToGo
+// //go:noescape
+// func copyBytesToGo(dst []byte, src ref) (int, bool)
+
+// CopyBytesToJS copies bytes from src to dst.
+// It panics if dst is not a Uint8Array or Uint8ClampedArray.
+// It returns the number of bytes copied, which will be the minimum of the lengths of src and dst.
+func CopyBytesToJS(dst Value, src []byte) int {
+	return 0
+	// n, ok := copyBytesToJS(dst.ref, src)
+	// runtime.KeepAlive(dst)
+	// if !ok {
+	// 	panic("syscall/js: CopyBytesToJS: expected dst to be a Uint8Array or Uint8ClampedArray")
+	// }
+	// return n
+}
+
+// copyBytesToJS copies bytes from src to dst.
+//
+// Using go:noescape is safe because the src byte slice is only used as a src
+// copy buffer and no references to it are maintained.
+//
+// //go:wasmimport gojs syscall/js.copyBytesToJS
+// //go:noescape
+// func copyBytesToJS(dst ref, src []byte) (int, bool)