> For the complete documentation index, see [llms.txt](https://paazmaya.gitbook.io/modern-web-tools-with-node-js/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://paazmaya.gitbook.io/modern-web-tools-with-node-js/quizzes/eslint.md).

# ESLint

ESLint is used to

|                              | yes  | no   |
| ---------------------------- | ---- | ---- |
| `compile JavaScript`         | \[ ] | \[x] |
| `check style issues`         | \[x] | \[ ] |
| `to detect unused variables` | \[x] | \[ ] |
| `measure code complexity`    | \[ ] | \[x] |
| `to detect division by zero` | \[x] | \[ ] |
| `enforce coding conventions` | \[x] | \[ ] |
| `measure test coverage`      | \[ ] | \[x] |

> ESLint performs static analysis of source code. See [ESLint.org](http://eslint.org/)

How do you install ESLint globally?

|                         | yes  | no   |
| ----------------------- | ---- | ---- |
| `install eslint`        | \[ ] | \[x] |
| `npm install eslint`    | \[ ] | \[x] |
| `npm install eslint -g` | \[x] | \[ ] |

> If you’re installing something that you want to use in your shell, on the command line or something, install it globally, so that its binaries end up in your PATH environment variable: `npm install eslint -g`

Which configuration options should be selected, if you want to set

* as errors: missing semicolon, empty block statements and use of constant expressions in conditions
* as warnings: whitespace at the end of line, mixed spaces and tabs for indentation (Smart Tabs off) and disallow labels that share a name with a variable
* other possible options off

|                                           | yes  | no   |
| ----------------------------------------- | ---- | ---- |
| `"semi": 1,`                              | \[ ] | \[x] |
| `"semicolon": 2,`                         | \[ ] | \[x] |
| `"semi": 2,`                              | \[x] | \[ ] |
| `"no-empty": 2,`                          | \[x] | \[ ] |
| `"no-empty": 1`                           | \[ ] | \[x] |
| `"no-empty-class": 1`                     | \[ ] | \[x] |
| `"no-constant-condition": 1,`             | \[ ] | \[x] |
| `"no-constant-condition": 2,`             | \[x] | \[ ] |
| `"no-trailing-spaces": 1,`                | \[x] | \[ ] |
| `"no-trailing-spaces": 2,`                | \[ ] | \[x] |
| `"no-plusplus": 2,`                       | \[ ] | \[x] |
| `"no-plusplus": 1,`                       | \[ ] | \[x] |
| `"no-mixed-spaces-and-tabs": [1, false],` | \[x] | \[ ] |
| `"no-mixed-spaces-and-tabs": [1, true],`  | \[ ] | \[x] |
| `"no-mixed-spaces-and-tabs": [2, false],` | \[ ] | \[x] |
| `"no-label-var": 1,`                      | \[x] | \[ ] |
| `"no-label-var": 2,`                      | \[ ] | \[x] |

> Hey, let's be careful out there!