Await

{#await expression}...{:then name}...{:catch name}...{/await}

{#await expression}...{:then name}...{/await}

{#await expression then name}...{/await}

await 可以让你处理 Promise 的三种状态 pending, fulfilled, rejected

{#await promise}
    <!-- promise is pending -->
    <p>waiting for the promise to resolve...</p>
{:then value}
    <!-- promise was fulfilled -->
    <p>The value is {value}</p>
{:catch error}
    <!-- promise was rejected -->
    <p>Something went wrong: {error.message}</p>
{/await}

如果Promise状态变为reject，或者发生错误时，你不需要渲染任何东西，则catch 块可以被忽略。

{#await promise}
    <!-- promise is pending -->
    <p>waiting for the promise to resolve...</p>
{:then value}
    <!-- promise was fulfilled -->
    <p>The value is {value}</p>
{/await}

如果你不关心pending状态，也可以省略初始化的状态。

{#await promise then value}
    <p>The value is {value}</p>
{/await}