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Merged
alexander-akait merged 5 commits into from
Apr 17, 2026
Merged

docs: clarify webpack loader execution order (right-to-left) #8136

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docs: clarify webpack loader execution order (right-to-left)
mr-baraiya Mar 29, 2026
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docs: clarify loader execution order and update example
mr-baraiya Mar 30, 2026
b19136c
docs: clarify loader execution order and update example to use postcs…
mr-baraiya Apr 16, 2026
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docs: clarify loader execution order, update example, and improve exp…
mr-baraiya Apr 16, 2026
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docs: fix mdx syntax and update loader example structure
mr-baraiya Apr 16, 2026
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17 changes: 12 additions & 5 deletions src/content/guides/asset-management.mdx
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Expand Up @@ -13,6 +13,7 @@ contributors:
- astonizer
- snitin315
- Brennvo
- mr-baraiya
---

If you've been following the guides from the start, you will now have a small project that shows "Hello webpack". Now let's try to incorporate some other assets, like images, to see how they can be handled.
Expand Down Expand Up @@ -95,15 +96,21 @@ npm install --save-dev style-loader css-loader
};
```

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Copilot AI Apr 16, 2026

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This section shows test: /\.css$/i in the config diff, but the explanatory sentence about test being a regex that selects which files the rule applies to was removed. Consider reintroducing a short explanation (e.g., that this rule targets .css files) so the example is self-contained for readers unfamiliar with webpack’s module.rules format.

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In this rule, `test: /\.css$/i` is a regular expression that tells webpack to apply the rule to `.css` files.

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Module loaders can be chained. Each loader in the chain applies transformations to the processed resource. A chain is executed in reverse order. The first loader passes its result (resource with applied transformations) to the next one, and so forth. Finally, webpack expects JavaScript to be returned by the last loader in the chain.
Loaders in webpack are executed from **right to left** (i.e., from last to first in the `use` array).

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Copilot AI Apr 16, 2026

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This section explains the general right-to-left execution order, but it no longer explicitly ties that back to the earlier use: ['style-loader', 'css-loader'] example (i.e., that css-loader runs first and style-loader runs last). Adding one short sentence that applies the rule to the preceding config would better resolve the original confusion this PR is addressing.

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The above order of loaders should be maintained: [`'style-loader'`](/loaders/style-loader) comes first and followed by [`'css-loader'`](/loaders/css-loader). If this convention is not followed, webpack is likely to throw errors.
For example:

T> webpack uses a regular expression to determine which files it should look for and serve to a specific loader. In this case, any file that ends with `.css` will be served to the `style-loader` and the `css-loader`.
```js
use: ['postcss-loader', 'sass-loader'],
```

In this rule, `test: /\.css$/i` is a regular expression that tells webpack to apply the rule to `.css` files.

Here, `sass-loader` runs first and compiles Sass into CSS, followed by `postcss-loader`, which applies further transformations.

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Copilot AI Apr 16, 2026

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The example references test: /\.css$/i and describes how the rule applies to .css files, but the shown use: ['postcss-loader', 'sass-loader'] chain typically corresponds to .scss/.sass input (and the snippet omits the test line entirely). Consider either showing the full rule (including test) with a matching extension for sass-loader, or switching the example loaders to ones that apply to .css so the explanation stays internally consistent.

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This enables you to `import './style.css'` into the file that depends on that styling. Now, when that module is run, a `<style>` tag with the stringified css will be inserted into the `<head>` of your html file.
So even though `postcss-loader` appears before `sass-loader` in the array, the execution happens in reverse order.

Let's try it out by adding a new `style.css` file to our project and import it in our `index.js`:
If this order is not maintained, webpack may throw errors.

**project**

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