如何在 Svelte/Sapper 中加载外部 JS 库?

问题描述

我一直在尝试加载 ace 编辑器 (https://ace.c9.io/)进入我的 Sapper 应用程序.当我在 Sapper 路由中加载它时，我在脚本标签中成功加载了它，但是当我尝试在 Svelte 组件中执行相同的操作时，该组件再次由路由呈现，我收到错误:

ace 未定义

这是我的代码，如果它是 Sapper 路线，它工作正常:

定义主():返回总和(范围(1,100))
<script src="https://pagecdn.io/lib/ace/1.4.6/ace.js" type="text/javascript" charset="utf-8"></script><脚本>var editor = ace.edit("editor");editor.setTheme("ace/theme/monokai");editor.session.setMode("ace/mode/python");editor.resize()

解决方案

当我第一次开始使用 Svelte2 时，我编写了一个组件来加载外部遗留 JS 库，然后将其重构为 Svelte 3.

//LibLoader.svelte<苗条:头><脚本绑定:this={script} src={url}/></svelte:head><脚本>import { onMount, createEventDispatcher } from 'svelte';const dispatch = createEventDispatcher();导出让网址；让脚本；onMount(async () => {script.addEventListener('load', () => {dispatch('加载');})script.addEventListener('error', (event) => {console.error("出了点问题", event);调度('错误');});});

//MyComponent.svelte<LibLoader url="myExternalLib.js"on:loaded="{onLoaded}"/><脚本>从'./LibLoader.svelte'导入LibLoader；函数 onLoaded() {myExternalLib.doStuff();}

这没有经过彻底的测试，一次性使用可能不保证单独的组件；但基本上这种方法解决了 Rich Harris 提到的时间问题.现在import 显然是更好的选择，如果有的话.

I have been trying to load the ace editor (https://ace.c9.io/) into my Sapper application. I had success loading it in the script tag when I loaded it in a Sapper route, but when I am trying to do the same in a Svelte component which is again rendered by a route I get the error:

ace is not defined

This is the code I have, which is working fine if it is a Sapper route:

<div id="editor"> def main():
    return sum(range(1,100))
</div>

    <script src="https://pagecdn.io/lib/ace/1.4.6/ace.js" type="text/javascript" charset="utf-8"></script>

    <script>
          var editor = ace.edit("editor");
          editor.setTheme("ace/theme/monokai");
          editor.session.setMode("ace/mode/python");
          editor.resize()
    </script>

解决方案

I hacked together a component to load external legacy JS libraries when I first started playing with Svelte2 and just refactored it to Svelte 3.

// LibLoader.svelte

<svelte:head>
  <script bind:this={script} src={url} />
</svelte:head>

<script>
  import { onMount, createEventDispatcher } from 'svelte';

  const dispatch = createEventDispatcher();
  export let url;
  let script;

  onMount(async () => {
    script.addEventListener('load', () => {
      dispatch('loaded');
    })

    script.addEventListener('error', (event) => {
      console.error("something went wrong", event);
      dispatch('error');
    });
  });
</script>

// MyComponent.svelte

<LibLoader url="myExternalLib.js"
on:loaded="{onLoaded}" />


<script>
  import LibLoader from './LibLoader.svelte';


  function onLoaded() {
    myExternalLib.doStuff();
  }
</script>

This is not thoroughly tested and for a one-off probably doesn't warrant a separate component; but basically the approach gets round the timing issue Rich Harris mentions. These days import is obviously the better option if it is available.

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