143 lines
3.6 KiB
Go
143 lines
3.6 KiB
Go
package wasm
|
|
|
|
import (
|
|
"fmt"
|
|
"syscall/js"
|
|
)
|
|
|
|
// TypeMismatchError is returned when a function is called with a js.Value that has the incorrect type.
|
|
type TypeMismatchError struct {
|
|
Expected js.Type
|
|
Actual js.Type
|
|
}
|
|
|
|
func (e TypeMismatchError) Error() string {
|
|
return fmt.Sprintf("expected %v type, got %v type instead", e.Expected, e.Actual)
|
|
}
|
|
|
|
// Global returns the global object as a Object.
|
|
// If the global object is not an object, it panics.
|
|
func Global() Object {
|
|
global, err := NewObject(js.Global())
|
|
if err != nil {
|
|
panic(err)
|
|
}
|
|
return global
|
|
}
|
|
|
|
// Object is a statically typed Object instance of js.Value.
|
|
// It should be instantiated with NewObject where it is checked for type instead of directly.
|
|
// Calling methods on a zero Object is undefined behaviour.
|
|
type Object struct {
|
|
value js.Value
|
|
}
|
|
|
|
// NewObject instantiates a new Object with the provided js.Value.
|
|
// If the js.Value is not an Object, it returns a TypeMismatchError.
|
|
func NewObject(raw js.Value) (Object, error) {
|
|
if raw.Type() != js.TypeObject {
|
|
return Object{}, TypeMismatchError{
|
|
Expected: js.TypeObject,
|
|
Actual: raw.Type(),
|
|
}
|
|
}
|
|
|
|
return Object{raw}, nil
|
|
}
|
|
|
|
// Get recursively gets the Object's properties, returning a TypeMismatchError if it encounters a non-object while
|
|
// descending through the object.
|
|
func (o Object) Get(path ...string) (js.Value, error) {
|
|
current := o.value
|
|
for _, v := range path {
|
|
if current.Type() != js.TypeObject {
|
|
return js.Value{}, TypeMismatchError{
|
|
Expected: js.TypeObject,
|
|
Actual: current.Type(),
|
|
}
|
|
}
|
|
|
|
current = current.Get(v)
|
|
}
|
|
return current, nil
|
|
}
|
|
|
|
// Expect is a helper function that calls Get and checks the type of the final result.
|
|
// It returns a TypeMismatchError if a non-object is encountered while descending the path or the final type does not
|
|
// match with the provided expected type.
|
|
func (o Object) Expect(expectedType js.Type, path ...string) (js.Value, error) {
|
|
value, err := o.Get(path...)
|
|
if err != nil {
|
|
return js.Value{}, err
|
|
}
|
|
|
|
if value.Type() != expectedType {
|
|
return js.Value{}, TypeMismatchError{
|
|
Expected: expectedType,
|
|
Actual: value.Type(),
|
|
}
|
|
}
|
|
|
|
return value, nil
|
|
}
|
|
|
|
// Delete removes property p from the object.
|
|
func (o Object) Delete(p string) {
|
|
o.value.Delete(p)
|
|
}
|
|
|
|
// Equal checks if the object is equal to another value.
|
|
// It is equivalent to JS's === operator.
|
|
func (o Object) Equal(v js.Value) bool {
|
|
return o.value.Equal(v)
|
|
}
|
|
|
|
// Index indexes into the object.
|
|
func (o Object) Index(i int) js.Value {
|
|
return o.value.Index(i)
|
|
}
|
|
|
|
// InstanceOf implements the instanceof operator in JavaScript.
|
|
// If t is not a constructor, this function returns false.
|
|
func (o Object) InstanceOf(t js.Value) bool {
|
|
if t.Type() != js.TypeFunction {
|
|
return false
|
|
}
|
|
return o.value.InstanceOf(t)
|
|
}
|
|
|
|
// JSValue implements the js.Wrapper interface.
|
|
func (o Object) JSValue() js.Value {
|
|
return o.value
|
|
}
|
|
|
|
// Length returns the "length" property of the object.
|
|
func (o Object) Length() int {
|
|
return o.value.Length()
|
|
}
|
|
|
|
// Set sets the property p to the value of ToJSValue(x).
|
|
func (o Object) Set(p string, x interface{}) {
|
|
o.value.Set(p, ToJSValue(x))
|
|
}
|
|
|
|
// SetIndex sets the index i to the value of ToJSValue(x).
|
|
func (o Object) SetIndex(i int, x interface{}) {
|
|
o.value.SetIndex(i, ToJSValue(x))
|
|
}
|
|
|
|
// String returns the object marshalled as a JSON string for debugging purposes.
|
|
func (o Object) String() string {
|
|
stringify, err := Global().Expect(js.TypeFunction, "JSON", "stringify")
|
|
if err != nil {
|
|
panic(err)
|
|
}
|
|
|
|
jsonStr := stringify.Invoke(o)
|
|
if jsonStr.Type() != js.TypeString {
|
|
panic("JSON.stringify returned a " + jsonStr.Type().String())
|
|
}
|
|
|
|
return jsonStr.String()
|
|
}
|