Combine Configs

In many cases, you won’t write an ESLint config file from scratch, but rather, you’ll use a combination of predefined and shareable configs along with your own overrides to create the config for your project. This page explains some of the patterns you can use to combine configs in your configuration file.

Apply a Config Object

If you are importing an object from another module, in most cases, you can just insert the object directly into your config file’s exported array. For example, you can use the recommended rule configurations for JavaScript by importing the recommended config and using it in your array:

// eslint.config.js
import js from "@eslint/js";

export default [
    js.configs.recommended,
    {
        rules: {
            "no-unused-vars": "warn"
        }
    }
];
1
2
3
4
5
6
7
8
9
10
11

Here, the js.configs.recommended predefined configuration is applied first and then another configuration object adds the desired configuration for no-unused-vars.

Apply a Config Object to a Subset of Files

You can apply a config object to just a subset of files by creating a new object with a files key and using the object spread operator to merge in the rest of the properties from the config object. For example:

// eslint.config.js
import js from "@eslint/js";

export default [
    {
        ...js.configs.recommended,
        files: ["**/src/safe/*.js"]
    }
];
1
2
3
4
5
6
7
8
9

Here, the js.configs.recommended config object is applied only to files that match the pattern "**/src/safe/*.js".

Apply a Config Array

If you are importing an array from another module, you can use the array spread operator to insert the items from that array into your exported array. Here’s an example:

// eslint.config.js
import exampleConfigs from "eslint-config-example";

export default [
    ...exampleConfigs,

    // your modifications
    {
        rules: {
            "no-unused-vars": "warn"
        }
    }
];
1
2
3
4
5
6
7
8
9
10
11
12
13

Here, the exampleConfigs shareable configuration is applied first and then another configuration object adds the desired configuration for no-unused-vars.

Apply a Config Array to a Subset of Files

You can apply a config array to just a subset of files by using the map() method to add a files key to each config object. For example:

// eslint.config.js
import exampleConfigs from "eslint-config-example";

export default [
    ...exampleConfigs.map(config => ({
        ...config,
        files: ["**/src/safe/*.js"]
    })),

    // your modifications
    {
        rules: {
            "no-unused-vars": "warn"
        }
    }
];
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16

Here, each config object in exampleConfigs is applied only to files that match the pattern "**/src/safe/*.js".