Documentation
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Overview ¶
Package js is the same api as syscall/js, but when not compiling under WASM target it panics.
The objective is to get tab completion to work inside an IDE (e.g. Visual Studio Code, GoLand) without having to change GOOS to js.
Original documentation:
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.
Index ¶
- func CopyBytesToGo(dst []byte, src Value) int
- func CopyBytesToJS(dst Value, src []byte) int
- type Error
- type Func
- type Type
- type Value
- func (v Value) Bool() bool
- func (v Value) Call(m string, args ...interface{}) Value
- func (v Value) Float() float64
- func (v Value) Get(p string) Value
- func (v Value) Index(i int) Value
- func (v Value) InstanceOf(t Value) bool
- func (v Value) Int() int
- func (v Value) Invoke(args ...interface{}) Value
- func (v Value) IsUndefined() bool
- func (v Value) JSValue() Value
- func (v Value) Length() int
- func (v Value) New(args ...interface{}) Value
- func (v Value) Set(p string, x interface{})
- func (v Value) SetIndex(i int, x interface{})
- func (v Value) String() string
- func (v Value) Truthy() bool
- func (v Value) Type() Type
- type ValueError
- type Wrapper
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func CopyBytesToGo ¶
CopyBytesToGo copies bytes from the Uint8Array src to dst. It returns the number of bytes copied, which will be the minimum of the lengths of src and dst. CopyBytesToGo panics if src is not an Uint8Array.
func CopyBytesToJS ¶
CopyBytesToJS copies bytes from src to the Uint8Array dst. It returns the number of bytes copied, which will be the minimum of the lengths of src and dst. CopyBytesToJS panics if dst is not an Uint8Array.
Types ¶
type Error ¶
type Error struct {
// Value is the underlying JavaScript error value.
Value
}
Error wraps a JavaScript error.
type Func ¶
type Func struct {
Value // the JavaScript function that invokes the Go function
}
Func is a wrapped Go function to be called by JavaScript.
func FuncOf ¶
FuncOf returns a wrapped function.
Invoking the JavaScript function will synchronously call the Go function fn 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.
A wrapped function triggered during a call from Go to JavaScript gets executed on the same goroutine. A wrapped function triggered by JavaScript's event loop gets executed on an extra goroutine. Blocking operations in the wrapped function will block the event loop. As a consequence, if one wrapped function blocks, other wrapped funcs will not be processed. A blocking function should therefore explicitly start a new goroutine.
Func.Release must be called to free up resources when the function will not be used any more.
type Value ¶
type Value struct {
}
Value represents a JavaScript value. The zero value is the JavaScript value "undefined".
func Global ¶
func Global() Value
Global returns the JavaScript global object, usually "window" or "global".
func ValueOf ¶
func ValueOf(x interface{}) Value
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 (Value) Call ¶
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 (Value) Float ¶
Float returns the value v as a float64. It panics if v is not a JavaScript number.
func (Value) Get ¶
Get returns the JavaScript property p of value v. It panics if v is not a JavaScript object.
func (Value) Index ¶
Index returns JavaScript index i of value v. It panics if v is not a JavaScript object.
func (Value) InstanceOf ¶
InstanceOf reports whether v is an instance of type t according to JavaScript's instanceof operator.
func (Value) Int ¶
Int returns the value v truncated to an int. It panics if v is not a JavaScript number.
func (Value) Invoke ¶
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 (Value) IsUndefined ¶
IsUndefined reports whether v is the JavaScript value "undefined".
func (Value) Length ¶
Length returns the JavaScript property "length" of v. It panics if v is not a JavaScript object.
func (Value) New ¶
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 (Value) Set ¶
Set sets the JavaScript property p of value v to ValueOf(x). It panics if v is not a JavaScript object.
func (Value) SetIndex ¶
SetIndex sets the JavaScript index i of value v to ValueOf(x). It panics if v is not a JavaScript object.
func (Value) String ¶
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 (Value) Truthy ¶
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.
type ValueError ¶
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.
func (*ValueError) Error ¶
func (e *ValueError) Error() string
Source Files