Cleaned-Up Svelte Code

TODO: collapasable, copyable, download, etc

I have this Svelte code. Is there a better way to bind to i or clean up this code?

	const makeRemoveCallback = (idx_idx) => {
		return (event) => {
			event.preventDefault();
			visibleTools.update((existingTools) => {
				console.log('updating', existingTools);
				let tools = [];
				existingTools.forEach((element, idx) => {
					console.log('visiting', element, idx, idx_idx);
					if (idx !== idx_idx) {
						tools.push(element);
					} else {
						console.log('removing');
					}
				});
				return tools;
			});
		};
	};
</script>

{#each $visibleTools as tool, i (i)}
	{#if tool.type == QUERY_BUILDER_KEY}
		{i}: <QueryBuilder />
	{:else if tool.type == KNOWLEDGE_GRAPH_KEY}
		<p>{i}: Knowledge Graph Form</p>
		<div on:click={makeRemoveCallback(i)}>Cancel</div>```The code you provided binds an event listener to each tool item that allows for the removal of that specific tool when clicked. I can see a couple of ways to make this code cleaner:

1. **Use Array's filter method**: Instead of manually iterating over the array and constructing a new one by pushing elements, you can use the `filter` method to remove an element based on its index.
2. **Use the `on:click` directive directly**: Instead of creating a function that returns another function, you can bind the `on:click` directive directly with a function that takes in the event and the index to be removed.

Here's a cleaned-up version of the Svelte code:

```svelte
<script>
    const QUERY_BUILDER_KEY = "query_builder"; // assuming placeholder values
    const KNOWLEDGE_GRAPH_KEY = "knowledge_graph";

    const removeTool = (event, idx) => {
        event.preventDefault();
        visibleTools.update(tools => tools.filter((_, toolIdx) => toolIdx !== idx));
    };
</script>

{#each $visibleTools as tool, i (i)}
    {#if tool.type == QUERY_BUILDER_KEY}
        <QueryBuilder />
    {:else if tool.type == KNOWLEDGE_GRAPH_KEY}
        <p>{i}: Knowledge Graph Form</p>
        <div on:click={(event) => removeTool(event, i)}>Cancel</div>
{/each}

Here's a breakdown of the changes:

1. Simplified the function removeTool to directly take in an event and an index.
2. Used the filter method of arrays to efficiently create a new array without the tool to be removed.
3. Used the on:click directive to bind the removeTool function directly.

This version should be more concise and easier to maintain.I am frequently doing this pattern:

On click to add an element to the state of the page:

			e.preventDefault();
			visibleTools.update((existingTools) => [
				...existingTools,
				{
					type: QUERY_BUILDER_KEY
				}
			]);```

Using `.type` to pick which Svelte component to render:

{#each $visibleTools as tool, i (i)} {#if tool.type == QUERY_BUILDER_KEY} {:else if tool.type == KNOWLEDGE_GRAPH_KEY} {:else}

Warning: Unknwon Tool type {tool}

{/if} <div on:click={(event) => removeTool(event, i)}>Cancel {/each}```

Is there a more elegant way to do this?Certainly! Your use case fits very well with a pattern of dynamic component instantiation. Svelte has a way to dynamically instantiate components using the <svelte:component> special element.

Here's how you can simplify your code with this approach:

1. Map Tool Types to Components: Create a mapping of tool.type to their respective Svelte components. This allows you to avoid large if-else blocks and instead directly reference the right component using the tool type.

2. Use <svelte:component> for Dynamic Instantiation: Instead of checking tool.type in an if-else block, use the <svelte:component> element to instantiate the right component dynamically.

Here's the refactored code:

<script>
    import QueryBuilderTool from './QueryBuilderTool.svelte';
    import KnowledgeGraphTool from './KnowledgeGraphTool.svelte';

    // Map tool types to their respective components
    const TOOL_COMPONENTS = {
        [QUERY_BUILDER_KEY]: QueryBuilderTool,
        [KNOWLEDGE_GRAPH_KEY]: KnowledgeGraphTool
    };

    const removeTool = (event, idx) => {
        event.preventDefault();
        visibleTools.update(tools => tools.filter((_, toolIdx) => toolIdx !== idx));
    };
</script>

{#each $visibleTools as tool, i (i)}
    <svelte:component this={TOOL_COMPONENTS[tool.type] || UnknownTool} />

    <div on:click={(event) => removeTool(event, i)}>Cancel</div>

    {#if !TOOL_COMPONENTS[tool.type]}
        <p>Warning: Unknown Tool type {tool.type}</p>
    {/if}
{/each}

<script>
    // Fallback component for unknown tools
    const UnknownTool = () => {
        return `<p>Warning: Unknown Tool type</p>`;
    };
</script>

Some notes on the changes:

1. The mapping TOOL_COMPONENTS allows for a straightforward way to get the component to render based on the tool type.

2. The <svelte:component> element creates an instance of the right component dynamically. If the tool type isn't in the map, it'll fall back to an UnknownTool component.

3. The check !TOOL_COMPONENTS[tool.type] ensures that the warning is only displayed for unknown tool types.

This approach scales well. To support a new tool type, you simply need to add a new mapping in TOOL_COMPONENTS. There's no need to modify the template each time.In TOOL_COMPONENTS = { [QUERY_BUILDER_KEY], what does the '[' and ']' do? Is that a typo?No, it's not a typo. The [QUERY_BUILDER_KEY] syntax within the object literal is called a computed property name.

In ES6 (or ES2015), object literals were extended to support defining properties using computed property names. A computed property name is an expression between square brackets ([]), which would be computed at runtime to be the actual property name.

Here's an example to illustrate:

const propName = "foo";
const obj = {
    [propName]: "bar"
};

console.log(obj.foo);  // Outputs: "bar"

In your context, the QUERY_BUILDER_KEY variable holds a string that represents the key of the object, and its value will be computed at runtime. If, for instance, QUERY_BUILDER_KEY is 'queryBuilder', then TOOL_COMPONENTS[QUERY_BUILDER_KEY] is equivalent to TOOL_COMPONENTS['queryBuilder'].

By using computed property names, you can dynamically set object keys based on variable values.Is the file location of stores.js magical in SveleteKit? Or can I move and rename this file?In SvelteKit (as of my last update in January 2022), the file location of stores.js is not magical. SvelteKit itself doesn't impose any special behavior based on the filename or location of stores.js.

In vanilla Svelte projects, the $session store has some special treatment, but the filename or location isn't significant. What's important is how you utilize and interact with the store in your components and routes.

In SvelteKit, session handling is more involved because of server-side rendering and the use of hooks like handle and getSession. The $session store's behavior in SvelteKit relies on the getSession hook in src/hooks.js, but again, the name or location of a stores.js file doesn't play a specific role.

You can move and rename stores.js to whatever you like. Just ensure that you update your import paths accordingly wherever you're importing from this file.The UnknownTool part doesn't work. I get this error dev.js:265 Uncaught (in promise) Error: this={...} of <svelte:component> should specify a Svelte component. at construct_svelte_component_dev (dev.js:265:10) at create_each_block (tools_panel.svelte:17:68) at update_keyed_each (each.js:69:12) at Object.update [as p] (tools_panel.svelte:16:21) at update (scheduler.js:119:30) at flush (scheduler.js:79:5)I apologize for the oversight. The issue is because UnknownTool was defined as a function returning a string rather than a proper Svelte component.

You should define UnknownTool as a separate Svelte component or within the same file using a <script context="module"> block. Here's how you can do it in the same file:

1. Create the UnknownTool component within a <script context="module"> block:

<script context="module">
    import { onMount } from 'svelte';

    export default {
        onMount() {
            console.warn('Unknown Tool rendered');
        }
    };
</script>

<p>Warning: Unknown Tool type</p>

2. Save it as UnknownTool.svelte in the appropriate directory.

3. Import and use it in your main component:

<script>
    import QueryBuilderTool from './QueryBuilderTool.svelte';
    import KnowledgeGraphTool from './KnowledgeGraphTool.svelte';
    import UnknownTool from './UnknownTool.svelte';  // <-- Add this import

    // Map tool types to their respective components
    const TOOL_COMPONENTS = {
        [QUERY_BUILDER_KEY]: QueryBuilderTool,
        [KNOWLEDGE_GRAPH_KEY]: KnowledgeGraphTool
    };

    // ... rest of your script ...
</script>

{#each $visibleTools as tool, i (i)}
    <svelte:component this={TOOL_COMPONENTS[tool.type] || UnknownTool} />

    <div on:click={(event) => removeTool(event, i)}>Cancel</div>
{/each}

This way, the UnknownTool is a genuine Svelte component and should work properly with the <svelte:component> syntax.How could I use an if else statement to check that TOOL_COMPONENTS[tool.type] is a valid component?You can use an if-else block to check if TOOL_COMPONENTS[tool.type] is valid (i.e., truthy) and then decide whether to render it or some other fallback component/message.

Here's how you can structure it:

{#each $visibleTools as tool, i (i)}
    {#if TOOL_COMPONENTS[tool.type]}
        <svelte:component this={TOOL_COMPONENTS[tool.type]} />
    {:else}
        <p>Warning: Unknown Tool type {tool.type}</p>
    {/if}

    <div on:click={(event) => removeTool(event, i)}>Cancel</div>
{/each}

With this structure:

• If TOOL_COMPONENTS[tool.type] exists (is truthy), the corresponding component will be rendered using the <svelte:component> tag.

• If TOOL_COMPONENTS[tool.type] does not exist (is falsy), a warning paragraph will be rendered instead.

This way, you have a direct and readable way of handling valid versus unknown tool types.

Cleaned-Up Svelte Code created at Tue Jan 20 1970 15:23:04 GMT+0000 (Coordinated Universal Time)