|
| 1 | +// +build js |
| 2 | + |
| 3 | +// Package wsjs implements typed access to the browser javascript WebSocket API. |
| 4 | +// https://developer.mozilla.org/en-US/docs/Web/API/WebSocket |
| 5 | +package wsjs |
| 6 | + |
| 7 | +import ( |
| 8 | + "context" |
| 9 | + "syscall/js" |
| 10 | +) |
| 11 | + |
| 12 | +func handleJSError(err *error, onErr func()) { |
| 13 | + r := recover() |
| 14 | + |
| 15 | + if jsErr, ok := r.(js.Error); ok { |
| 16 | + *err = jsErr |
| 17 | + |
| 18 | + if onErr != nil { |
| 19 | + onErr() |
| 20 | + } |
| 21 | + return |
| 22 | + } |
| 23 | + |
| 24 | + if r != nil { |
| 25 | + panic(r) |
| 26 | + } |
| 27 | +} |
| 28 | + |
| 29 | +func New(ctx context.Context, url string, protocols []string) (c *WebSocket, err error) { |
| 30 | + defer handleJSError(&err, func() { |
| 31 | + c = nil |
| 32 | + }) |
| 33 | + |
| 34 | + jsProtocols := make([]interface{}, len(protocols)) |
| 35 | + for i, p := range protocols { |
| 36 | + jsProtocols[i] = p |
| 37 | + } |
| 38 | + |
| 39 | + c = &WebSocket{ |
| 40 | + v: js.Global().Get("WebSocket").New(url, jsProtocols), |
| 41 | + } |
| 42 | + |
| 43 | + c.setBinaryType("arrayBuffer") |
| 44 | + |
| 45 | + c.Extensions = c.v.Get("extensions").String() |
| 46 | + c.Protocol = c.v.Get("protocol").String() |
| 47 | + c.URL = c.v.Get("url").String() |
| 48 | + |
| 49 | + return c, nil |
| 50 | +} |
| 51 | + |
| 52 | +type WebSocket struct { |
| 53 | + Extensions string |
| 54 | + Protocol string |
| 55 | + URL string |
| 56 | + |
| 57 | + v js.Value |
| 58 | +} |
| 59 | + |
| 60 | +func (c *WebSocket) setBinaryType(typ string) { |
| 61 | + c.v.Set("binaryType", string(typ)) |
| 62 | +} |
| 63 | + |
| 64 | +func (c *WebSocket) BufferedAmount() uint32 { |
| 65 | + return uint32(c.v.Get("bufferedAmount").Int()) |
| 66 | +} |
| 67 | + |
| 68 | +func (c *WebSocket) addEventListener(eventType string, fn func(e js.Value)) { |
| 69 | + c.v.Call("addEventListener", eventType, js.FuncOf(func(this js.Value, args []js.Value) interface{} { |
| 70 | + fn(args[0]) |
| 71 | + return nil |
| 72 | + })) |
| 73 | +} |
| 74 | + |
| 75 | +type CloseEvent struct { |
| 76 | + Code uint16 |
| 77 | + Reason string |
| 78 | + WasClean bool |
| 79 | +} |
| 80 | + |
| 81 | +func (c *WebSocket) OnClose(fn func(CloseEvent)) { |
| 82 | + c.addEventListener("close", func(e js.Value) { |
| 83 | + ce := CloseEvent{ |
| 84 | + Code: uint16(e.Get("code").Int()), |
| 85 | + Reason: e.Get("reason").String(), |
| 86 | + WasClean: e.Get("wasClean").Bool(), |
| 87 | + } |
| 88 | + fn(ce) |
| 89 | + }) |
| 90 | +} |
| 91 | + |
| 92 | +func (c *WebSocket) OnError(fn func(e js.Value)) { |
| 93 | + c.addEventListener("error", fn) |
| 94 | +} |
| 95 | + |
| 96 | +type MessageEvent struct { |
| 97 | + Data []byte |
| 98 | + // There are more types to the interface but we don't use them. |
| 99 | + // See https://developer.mozilla.org/en-US/docs/Web/API/MessageEvent |
| 100 | +} |
| 101 | + |
| 102 | +func (c *WebSocket) OnMessage(fn func(m MessageEvent)) { |
| 103 | + c.addEventListener("message", func(e js.Value) { |
| 104 | + var data []byte |
| 105 | + |
| 106 | + arrayBuffer := e.Get("data") |
| 107 | + if arrayBuffer.Type() == js.TypeString { |
| 108 | + data = []byte(arrayBuffer.String()) |
| 109 | + } else { |
| 110 | + data = extractArrayBuffer(arrayBuffer) |
| 111 | + } |
| 112 | + |
| 113 | + me := MessageEvent{ |
| 114 | + Data: data, |
| 115 | + } |
| 116 | + fn(me) |
| 117 | + |
| 118 | + return |
| 119 | + }) |
| 120 | +} |
| 121 | + |
| 122 | +func (c *WebSocket) OnOpen(fn func(e js.Value)) { |
| 123 | + c.addEventListener("open", fn) |
| 124 | +} |
| 125 | + |
| 126 | +func (c *WebSocket) Close(code int, reason string) (err error) { |
| 127 | + defer handleJSError(&err, nil) |
| 128 | + c.v.Call("close", code, reason) |
| 129 | + return err |
| 130 | +} |
| 131 | + |
| 132 | +func (c *WebSocket) SendText(v string) (err error) { |
| 133 | + defer handleJSError(&err, nil) |
| 134 | + c.v.Call("send", v) |
| 135 | + return err |
| 136 | +} |
| 137 | + |
| 138 | +func (c *WebSocket) SendBytes(v []byte) (err error) { |
| 139 | + defer handleJSError(&err, nil) |
| 140 | + c.v.Call("send", uint8Array(v)) |
| 141 | + return err |
| 142 | +} |
| 143 | + |
| 144 | +func extractArrayBuffer(arrayBuffer js.Value) []byte { |
| 145 | + uint8Array := js.Global().Get("Uint8Array").New(arrayBuffer) |
| 146 | + dst := make([]byte, uint8Array.Length()) |
| 147 | + js.CopyBytesToGo(dst, uint8Array) |
| 148 | + return dst |
| 149 | +} |
| 150 | + |
| 151 | +func uint8Array(src []byte) js.Value { |
| 152 | + uint8Array := js.Global().Get("Uint8Array").New(len(src)) |
| 153 | + js.CopyBytesToJS(uint8Array, src) |
| 154 | + return uint8Array |
| 155 | +} |
0 commit comments