Comprehensive Front-End Code Review Checklist and Best Practices

The article provides a thorough front‑end code review checklist, emphasizing eight key review dimensions: code quality, functionality, performance, security, testability, readability, reusability, and compatibility.

Code Quality & Functionality Review

Reviewers should ensure code is concise, readable, follows style guides (ESLint, Prettier), implements expected features without bugs, and includes appropriate unit tests.

Performance Review

Common performance pitfalls include excessive rendering, heavy DOM manipulation, numerous network requests, large JavaScript bundles, unoptimized media, and render‑blocking CSS/JS. Strategies such as using <script async>, <script defer>, inline critical CSS, and media queries are recommended.

<script async src="script.js"></script>

<script defer src="script.js"></script>

<style>
  /* Critical CSS */
</style>

<link rel="stylesheet" media="(max-width: 600px)" href="mobile.css">

Readability Review

Focus on semantic naming, comments, documentation, and clear TypeScript type declarations.

Reusability Review

Assess whether code can be encapsulated as functions, classes, directives, hooks, components, or modules for better reuse.

Security Review

Key security checks include XSS protection (avoid dangerouslySetInnerHTML or v-html), CSRF tokens, click‑jacking defenses via X-Frame-Options, HTTPS usage, input validation, avoiding sensitive data leaks, and keeping third‑party dependencies up‑to‑date.

X-Frame-Options: DENY

X-Frame-Options: SAMEORIGIN

Compatibility Review

Ensure cross‑browser, device, and responsive compatibility, and consider accessibility (WAI‑ARIA) and internationalization.

Polyfill Guidance

Polyfills provide missing features in older browsers. Example for Array.prototype.includes:

if (!Array.prototype.includes) {
  Array.prototype.includes = function(element) {
    return this.indexOf(element) !== -1;
  };
}

Configuration with core-js and @babel/preset-env is illustrated, showing useBuiltIns set to "usage" or "entry" and the corresponding .babelrc snippet.

{
  "presets": [
    ["@babel/preset-env", {
      "useBuiltIns": "usage",
      "corejs": 3
    }]
  ]
}

Testability Review

Assess unit, integration, and end‑to‑end (E2E) testability, test coverage, mocking, and error handling.

E2E Testing Example (Cypress)

describe('Login Test', function() {
  it('Successfully logs in', function() {
    cy.visit('/login');
    cy.get('input[name=username]').type('testuser');
    cy.get('input[name=password]').type('testpassword');
    cy.get('button[type=submit]').click();
    cy.url().should('include', '/home');
    cy.get('h1').should('contain', 'Welcome, testuser');
  });
});

Run the tests with npx cypress open. The article concludes with a mnemonic "功性读复全兼测" to remember the review dimensions.