svelte-lancer

Lightweight utility class (<5kb) that makes using SvelteKit's enhance actions easy and compact using the power of stores! Get rid of repetitive code that tracks if your form is still loading.

Available through the npm registry, use your preferred package manager to install.

$ npm install -D svelte-lancer

Quick Start

Using SvelteLancer is at its most basic looks like this:

<script lang="ts">
    import { enhance } from "$app/forms";
    import { SvelteLancer } from "svelte-lancer";
    const lancer = new SvelteLancer();
</script>

<form method="POST" use:enhance={lancer.submit}>
    <button disabled={$lancer.loading}>Click Me!</button>
</form>

Compare to what would be needed by writing a SubmitFunction:

<script lang="ts">
    import { type SubmitFunction, enhance } from "$app/forms";
    let loading = false;
    const submit: SubmitFunction = () => {
        loading = true;
        return async ({ result, update }) => {
            await update();
            loading = false;
        };
    };
</script>

<form method="POST" use:enhance={submit}>
    <button disabled={loading}>Click Me!</button>
</form>

Prevent Disable Flicker After Redirect

With SvelteLancer:

<script lang="ts">
    import { enhance } from "$app/forms";
    import { SvelteLancer } from "svelte-lancer";
    const lancer = new SvelteLancer();
    $: disabled = $lancer.loading || $lancer.count.redirect;
</script>

<form method="POST" use:enhance={lancer.submit}>
    <button {disabled}>Log In</button>
</form>

With SubmitFunction:

<script lang="ts">
    import { type SubmitFunction, enhance } from "$app/forms";
    let loading = false;
    const submit: SubmitFunction = () => {
        loading = true;
        return async ({ result, update }) => {
            await update();
            if (result.type !== "redirect") loading = false;
        };
    };
</script>

<form method="POST" use:enhance={submit}>
    <button disabled={loading}>Log In</button>
</form>

Prevent Rendering Error Page

With SvelteLancer:

<script lang="ts">
    import { enhance } from "$app/forms";
    import { SvelteLancer } from "svelte-lancer";
    const lancer = new SvelteLancer().on("error", () => console.log("no-op"));
</script>

<form method="POST" use:enhance={lancer.submit}>
    <button disabled={$lancer.loading}>Might Error...</button>
</form>

With SubmitFunction:

<script lang="ts">
    import { type SubmitFunction, enhance } from "$app/forms";
    let loading = false;
    const submit: SubmitFunction =
        () => {
            loading = true;
            return ({ result, update }) => {
                loading = false;
                if (result.type !== "error") await update();
                else console.log("no-op");
                loading = false;
            };
        }
</script>

<form method="POST" use:enhance={submit}>
    <button disabled={loading}>Might Error...</button>
</form>

Demo Project

Check out src/routes/+page.svelte for more reference. It is deployed at https://svelte-lancer.vercel.app/