|
| 1 | +--- |
| 2 | +title: Client |
| 3 | +description: Use the generated sse() function for type-safe Server-Sent Event streams with React, Svelte, and vanilla TypeScript. |
| 4 | +sidebar: |
| 5 | + order: 2 |
| 6 | +--- |
| 7 | + |
| 8 | +:::caution |
| 9 | +The SSE client API is experimental. The API may change in future releases. |
| 10 | +::: |
| 11 | + |
| 12 | +`shiftapi prepare` generates a fully-typed `sse` function constrained to SSE paths only — calling `sse` on a non-SSE path is a compile-time error. |
| 13 | + |
| 14 | +## Basic usage |
| 15 | + |
| 16 | +`sse` returns an async iterable stream with a `close()` method: |
| 17 | + |
| 18 | +```typescript |
| 19 | +import { sse } from "@shiftapi/client"; |
| 20 | + |
| 21 | +const stream = sse("/events", { |
| 22 | + params: { query: { channel: "general" } }, |
| 23 | +}); |
| 24 | + |
| 25 | +for await (const event of stream) { |
| 26 | + console.log(event); |
| 27 | + // ^? ChatEvent — fully typed |
| 28 | +} |
| 29 | +``` |
| 30 | + |
| 31 | +To stop the stream: |
| 32 | + |
| 33 | +```typescript |
| 34 | +stream.close(); |
| 35 | +``` |
| 36 | + |
| 37 | +You can also pass an `AbortSignal`: |
| 38 | + |
| 39 | +```typescript |
| 40 | +const controller = new AbortController(); |
| 41 | +const stream = sse("/events", { signal: controller.signal }); |
| 42 | + |
| 43 | +// later... |
| 44 | +controller.abort(); |
| 45 | +``` |
| 46 | + |
| 47 | +## Path parameters and headers |
| 48 | + |
| 49 | +Path parameters and request headers are type-checked. If your Go handler declares `path:"room_id"` or `header:"X-Token"` on the input struct, the generated types require them: |
| 50 | + |
| 51 | +```typescript |
| 52 | +const stream = sse("/rooms/{room_id}/events", { |
| 53 | + params: { |
| 54 | + path: { room_id: "abc" }, |
| 55 | + header: { "X-Token": "secret" }, |
| 56 | + }, |
| 57 | +}); |
| 58 | +``` |
| 59 | + |
| 60 | +## Discriminated unions |
| 61 | + |
| 62 | +For endpoints that emit multiple event types (registered with `SSESends` on the Go side), the generated client narrows event types based on the `event` field: |
| 63 | + |
| 64 | +```typescript |
| 65 | +import { sse } from "@shiftapi/client"; |
| 66 | + |
| 67 | +const stream = sse("/chat"); |
| 68 | + |
| 69 | +for await (const msg of stream) { |
| 70 | + if (msg.event === "message") { |
| 71 | + console.log(msg.data.text); |
| 72 | + // ^? string — narrowed to MessageData |
| 73 | + } else if (msg.event === "join") { |
| 74 | + console.log(msg.data.user); |
| 75 | + // ^? string — narrowed to JoinData |
| 76 | + } |
| 77 | +} |
| 78 | +``` |
| 79 | + |
| 80 | +## React |
| 81 | + |
| 82 | +Use `sse` with React state. You control how events are accumulated: |
| 83 | + |
| 84 | +```tsx |
| 85 | +import { sse } from "@shiftapi/client"; |
| 86 | +import { useEffect, useState } from "react"; |
| 87 | + |
| 88 | +function ChatFeed() { |
| 89 | + const [messages, setMessages] = useState<ChatEvent[]>([]); |
| 90 | + |
| 91 | + useEffect(() => { |
| 92 | + const stream = sse("/chat"); |
| 93 | + (async () => { |
| 94 | + for await (const event of stream) { |
| 95 | + setMessages((prev) => [...prev, event]); |
| 96 | + } |
| 97 | + })(); |
| 98 | + return () => stream.close(); |
| 99 | + }, []); |
| 100 | + |
| 101 | + return ( |
| 102 | + <ul> |
| 103 | + {messages.map((msg, i) => ( |
| 104 | + <li key={i}>{msg.user}: {msg.message}</li> |
| 105 | + ))} |
| 106 | + </ul> |
| 107 | + ); |
| 108 | +} |
| 109 | +``` |
| 110 | + |
| 111 | +For a "latest value" pattern (dashboards, tickers): |
| 112 | + |
| 113 | +```tsx |
| 114 | +function TickerDisplay() { |
| 115 | + const [tick, setTick] = useState<Tick | null>(null); |
| 116 | + |
| 117 | + useEffect(() => { |
| 118 | + const stream = sse("/ticks"); |
| 119 | + (async () => { |
| 120 | + for await (const event of stream) setTick(event); |
| 121 | + })(); |
| 122 | + return () => stream.close(); |
| 123 | + }, []); |
| 124 | + |
| 125 | + if (!tick) return <div>Connecting...</div>; |
| 126 | + return <div>Last tick: {tick.time}</div>; |
| 127 | +} |
| 128 | +``` |
| 129 | + |
| 130 | +## Svelte |
| 131 | + |
| 132 | +```svelte |
| 133 | +<script> |
| 134 | + import { sse } from "@shiftapi/client"; |
| 135 | +
|
| 136 | + let messages = []; |
| 137 | +
|
| 138 | + const stream = sse("/chat"); |
| 139 | + (async () => { |
| 140 | + for await (const event of stream) { |
| 141 | + messages = [...messages, event]; |
| 142 | + } |
| 143 | + })(); |
| 144 | +</script> |
| 145 | +
|
| 146 | +<ul> |
| 147 | + {#each messages as msg} |
| 148 | + <li>{msg.user}: {msg.message}</li> |
| 149 | + {/each} |
| 150 | +</ul> |
| 151 | +``` |
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