How to ass cssHash i see warning : [vite-plugin-svelte] The following Svelte compilerOptions are controlled by vite-plugin-svelte and essential to its functionality

[good-dev-student]

Hello,

please help me

The goal is to change classes like this :

<div class="xx s-OTmmHBhb3fXp" data-svelte-h="svelte-g8ovga">c</div>

to this :

<div class="xx s-OTmmHBhb3fXp" data-svelte-h="meaw-g8ovga">c</div>

I add the code to svelte.config.js :

compilerOptions: {
		cssHash: ({ hash, name, filename, css }) => {
			// default behavior
			//return `svelte-${hash(css)}`;
		
			// stable hashes for HMR
			return `wohh-${hash(filename)}`;
		  }

	},

Final code like this:

import adapter from '@sveltejs/adapter-auto';
import { vitePreprocess } from '@sveltejs/kit/vite';

/** @type {import('@sveltejs/kit').Config} */
const config = {
+	compilerOptions: {
+		cssHash: ({ hash, name, filename, css }) => {
+			// default behavior
+			//return `svelte-${hash(css)}`;
+		
+			// stable hashes for HMR
+			return `svelte-${hash(filename)}`;
+		  }
+
	},
	// Consult https://kit.svelte.dev/docs/integrations#preprocessors
	// for more information about preprocessors
	preprocess: [vitePreprocess({})],

	kit: {
		// adapter-auto only supports some environments, see https://kit.svelte.dev/docs/adapter-auto for a list.
		// If your environment is not supported or you settled on a specific environment, switch out the adapter.
		// See https://kit.svelte.dev/docs/adapters for more information about adapters.
		adapter: adapter()
	},
};

export default config;

i will see WARNING like thsis:

[vite-plugin-svelte] The following Svelte compilerOptions are controlled by vite-plugin-svelte and essential to its functionality. User-specified values are ignored. Please remove them from your configuration: cssHash

in vite.config.ts not working

NOT like this:

import { sveltekit } from '@sveltejs/kit/vite';
import { defineConfig } from 'vitest/config';

export default defineConfig({
	plugins: [
		sveltekit({
			compilerOptions: {
				cssHash: ({ hash }) => hash('foo')
			}
		})
	],

	test: {
		include: ['src/**/*.{test,spec}.{js,ts}']
	},

	css: {
		preprocessorOptions: {
			scss: {
				additionalData: '@use "src/scss/variables.scss" as *;'
			}
		}
	}
});

or this:

import { sveltekit } from '@sveltejs/kit/vite';
import { defineConfig } from 'vitest/config';

export default defineConfig({
	
	plugins: [sveltekit()],

	test: {
		include: ['src/**/*.{test,spec}.{js,ts}']
	},

	css: {
		preprocessorOptions: {
			scss: {
				additionalData: '@use "src/scss/variables.scss" as *;'
			}
		}
	},
	compilerOptions: {
		cssHash: ({ hash }) => hash('foo')
	}
});

[good-dev-student]

And if i want to change the cssHash on dev also dosen't work idk why and why work only on prod?

import adapter from '@sveltejs/adapter-auto';
import { vitePreprocess } from '@sveltejs/kit/vite';

const compilerOptions = {};

// if (process.env.NODE_ENV === 'production') {
    compilerOptions.cssHash = ({ hash, css }) => `ai-${hash(css)}`;
// }

/** @type {import('@sveltejs/kit').Config} */
const config = {
    // Consult https://kit.svelte.dev/docs/integrations#preprocessors
    // for more information about preprocessors
    preprocess: [vitePreprocess({})],

    kit: {
        // adapter-auto only supports some environments, see https://kit.svelte.dev/docs/adapter-auto for a list.
        // If your environment is not supported or you settled on a specific environment, switch out the adapter.
        // See https://kit.svelte.dev/docs/adapters for more information about adapters.
        adapter: adapter()
    },
    compilerOptions
};

export default config;

[ala-garbaa-pro]

It looks like you are trying to customize the cssHash in a SvelteKit project, but you are encountering some issues. Let me try to help you with that.

Firstly, the warning you are seeing about cssHash is likely because you are trying to override it in the wrong place. The cssHash should be set in the compilerOptions under kit in your svelte.config.js, not at the top level of compilerOptions. Here's how you can update your svelte.config.js:

import adapter from '@sveltejs/adapter-auto';
import { vitePreprocess } from '@sveltejs/kit/vite';

const config = {
    // Consult https://kit.svelte.dev/docs/integrations#preprocessors
    // for more information about preprocessors
    preprocess: [vitePreprocess({})],

    kit: {
        // adapter-auto only supports some environments, see https://kit.svelte.dev/docs/adapter-auto for a list.
        // If your environment is not supported or you settled on a specific environment, switch out the adapter.
        // See https://kit.svelte.dev/docs/adapters for more information about adapters.
        adapter: adapter(),
        compilerOptions: {
            cssHash: ({ hash, filename, css }) => {
                // customize your cssHash here
                return `meaw-${hash(filename)}`;
            }
        }
    },
};

export default config;

In this example, I've moved the cssHash inside compilerOptions under kit.

As for changing the cssHash in development, you can conditionally set it based on the environment. You can use process.env.NODE_ENV to check if it's in production or development. If you want to apply a different cssHash in development, you can do something like this:

const config = {
    // ...

    kit: {
        // ...
        compilerOptions: {
            cssHash: ({ hash, filename, css }) => {
                if (process.env.NODE_ENV === 'production') {
                    return `ai-${hash(css)}`;
                } else {
                    // customize your development cssHash here
                    return `dev-${hash(css)}`;
                }
            },
        },
    },
};

export default config;

This way, you can have different cssHash values for production and development environments. Make sure to restart your development server after making these changes.

[debuggerpk]

this is a wrong answer as of https://github.com/sveltejs/kit/blob/main/packages/kit/types/index.d.ts#L262

and the compiler gives an error.

Could not load svelte.config.js: Unexpected option config.kit.compilerOptions

[andremacola]

So.. what's the ideal solution for this?

[Randall3475]

You should put it after kit:

const config = { preprocess: preprocess(), kit: { adapter: adapter() }, compilerOptions: { cssHash: ({ hash, filename, css }) => { return meaw-${hash(filename)}; } } };

Also, it will not work in development. Refer to here: https://github.com/sveltejs/vite-plugin-svelte/blob/main/docs/faq.md#why-cant-csshash-be-set-in-development-mode

Why can't cssHash be set in development mode?

cssHash is fixed in development for CSS HMR in Svelte components, ensuring that the hash value is stable based on the file name so that styles are only updated when changed.

However, cssHash is respected in production builds as HMR is a dev-only feature.