Hey there, I’ve been in your shoes before—nothing’s more frustrating than seeing that red Travis CI mark pop up when your Jest tests pass perfectly! Let’s break down your questions to get you submitting clean PRs in no time:

1. Is there a way to fix indentation without manually editing every line? #

Absolutely—you don’t have to slog through each line one by one. Here are the easiest fixes:

• Use your linter’s auto-fix command: Most linters (like ESLint, which is common in JS projects paired with Jest) have an auto-fix flag. Run this in your terminal to fix a single file:

  eslint --fix path/to/your/file.js
  

  To fix multiple files at once, use a wildcard pattern:

  eslint --fix src/**/*.js
  

• Check for project-specific npm scripts: Many projects add a dedicated fix script in package.json. Look for something like "lint:fix": "eslint --fix ."—if it exists, just run npm run lint:fix and let the tool handle the rest.
• IDE auto-formatting: Set up your code editor to fix issues on save. For example, in VS Code:
  1. Install the ESLint extension.
  2. Go to Settings > Search for "ESLint: Auto Fix On Save" and enable it.
     This will automatically adjust indentation (and other fixable rules) every time you save your file.
• Prettier integration: If the project uses Prettier alongside ESLint, Prettier handles formatting rules like indentation seamlessly. Run npx prettier --write path/to/your/file.js or set it up to run on save for instant fixes.

2. Are lint rules standardized or custom-configured by the project? #

Lint rules are almost always custom-configured by the project maintainers, not a universal standard. While linters like ESLint have default rules, projects will override these in configuration files (like .eslintrc.json, .eslintrc.js, or .eslintrc.yml) to match their team’s preferred style.

In your case, the project clearly enforces 2-space indentation, but you’re using 4 spaces—hence all those errors. Some projects also use shared rule sets (like eslint-config-airbnb or eslint-config-standard) as a base, then tweak rules to fit their specific needs.

3. How can I quickly learn a new GitHub project’s code style requirements? #

Here’s how to get up to speed fast:

• Read the CONTRIBUTING guide: Most open source projects have a CONTRIBUTING.md file in the root directory. It will explicitly outline code style rules, which linters to use, and how to run checks locally before submitting a PR.
• Check configuration files: Look for files like .eslintrc, .prettierrc, or .editorconfig in the project root. These files are the source of truth for code style—you can see exactly what indentation, quote style, line length, etc., are required.
• Examine existing code: Open a few well-established files in the project (like core components or utility functions) and observe their formatting. Pay attention to indentation, where newlines are added, how functions are structured, and comment styles.
• Run local lint checks early: Before committing changes, run the project’s lint command (usually npm run lint or yarn lint) to catch issues before they hit CI. This saves you from waiting for Travis to fail and lets you fix problems immediately.

Example Lint Errors You Shared #

3:1 error Expected indentation of 2 spaces but found 4 indent
4:1 error Expected indentation of 2 spaces but found 4 indent
5:1 error Expected indentation of 2 spaces but found 4 indent
6:1 error Expected indentation of 2 spaces but found 4 indent
7:1 error Expected indentation of 2 spaces but found 4 indent
17:1 error Expected indentation of 2 spaces but found 4 indent
18:1 error Expected indentation of 4 spaces but found 8 indent
19:1 error Expected indentation of 2 spaces but found 4 indent
21:1 error Expected indentation of 2 spaces but found 4 indent
22:1 error Expected indentation of 4 spaces but found 8 indent
23:1 error Expected indentation of 2 spaces but found 4 indent
25:1 error Expected indentation of 2 spaces but found 4 indent
26:1 error Expected indentation of 4 spaces but found 8 indent
27:1 error Expected indentation of 2 spaces but found 4 indent
29:1 error Expected indentation of 2 spaces but found 4 indent
30:1 error Expected indentation of 4 spaces but found 8 indent
31:1 error Expected indentation of 2 spaces but found 4 indent
33:1 error Expected indentation of 2 spaces but found 4 indent
34:1 error Expected indentation of 4 spaces but found 8 indent
35:1 error Expected indentation of 6 spaces but found 12 indent
36:1 error Expected indentation of 6 spaces but found 12 indent
37:1 error Expected indentation of 6 spaces but found 12 indent
38:1 error Expected indentation of 4 spaces but found 8 indent
39:1 error Expected indentation of 2 spaces but found 4 indent
41:1 error Expected indentation of 2 spaces but found 4 indent
42:1 error Expected indentation of 4 spaces but found 8 indent
43:1 error Expected indentation of 6 spaces but found 12 indent
44:1 error Expected indentation of 6 spaces but found 12 indent
45:1 error Expected indentation of 6 spaces but found 12 indent
46:1 error Expected indentation of 4 spaces but found 8 indent
47:1 error Expected indentation of 2 spaces but found 4 indent
49:1 error Expected indentation of 2 spaces but found 4 indent
50:1 error Expected indentation of 4 spaces but found 8 indent
51:1 error Expected indentation of 6 spaces but found 12 indent
52:1 error Expected indentation of 6 spaces but found 12 indent
53:1 error Expected indentation of 6 spaces but found 12 indent
54:1 error Expected indentation of 4 spaces but found 8 indent
55:1 error Expected indentation of 2 spaces but found 4 indent
57:1 error Expected indentation of 2 spaces but found 4 indent
58:1 error Expected indentation of 4 spaces but found 8 indent
59:1 error Expected indentation of 6 spaces but found 12 indent
60:1 error Expected indentation of 6 spaces but found 12 indent
61:1 error Expected indentation of 6 spaces but found 12 indent
62:1 error Expected indentation of 4 spaces but found 8 indent
63:1 error Expected indentation of 2 spaces but found 4 indent

内容的提问来源于stack exchange，提问作者Wolf_Tru