jrDev

Master the real-world skills every junior developer needs.

Why Reading Code Matters

Why Reading Code Matters

Most beginners think being a “good developer” means writing code quickly. In the real world, it’s the opposite: Software engineering is reading.

Studies and common industry wisdom suggest a “Reading to Writing Ratio” of about 10 to 1. For every line of code you write, you will read at least ten others.

The 90/10 Rule

Writing Code [10%]   ||||| 
Reading Code [90%]   ||||||||||||||||||||||||||||||||||||||||||||||||||

Why Do We Read So Much?

  1. Maintenance: Most code you work on already exists. You have to read it to change it.
  2. Context: You can’t add a new feature without understanding how the current system works.
  3. Reviewing: Peer reviews (PRs) are a huge part of your job. You read your teammates’ code to find bugs or learn.
  4. Learning: Want to know how React or Django works? You have to read the source.

Real-World Example: The “Quick Fix”

Imagine a bug report: “The logout button doesn’t clear the session.”

  • Bad Approach: Jump straight into LogoutButton.js and start writing code.
  • Good Approach:
    1. Read AuthContext.js to see how sessions are handled.
    2. Read SessionManager.ts to see what “clearing” actually means.
    3. Read ApiCaller.js to see if a logout request is even being sent.
    4. Finally, write two lines of code to fix the issue.

Reading for 20 minutes saves you 2 hours of writing the wrong fix.

Common Mistake: “I’ll Just Rewrite It”

Juniors often look at complex code they don’t understand and think, “This is messy, I’ll just rewrite it.” This is a trap. The code might be complex because it handles 50 edge cases you don’t know about yet. Read first, rewrite (maybe) second.

Practical Strategy: The “Mental Debugger”

When reading, try to act like the computer. What is the value of x right now? If this if statement is true, where do I go next?

Mental Model: The Library

Think of a codebase like a massive library. You don’t need to read every book to find the information you need, but you must know how to use the index and the Dewey Decimal System (the project structure).

Next: How to Approach a New Codebase