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1. Reject any, Embrace Types#

any is TypeScript’s escape hatch, but if you use it too much, it just becomes AnyScript.

• Bad smell: function process(data: any) { ... }
• Refactor: Even if you don’t know the exact type, please use unknown, which forces you to perform Type Narrowing before use. Or define an interface, even if it only has some of the fields.

2. Guard Clauses Instead of Nested ifs#

Don’t write “arrowhead” code (nested too deeply).

Bad:

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function processUser(user: User) {
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  if (user != null) {
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    if (user.isActive) {
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      if (user.hasCredit) {
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         // Core logic...
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      }
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    }
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  }
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}

Good:

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function processUser(user: User) {
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  if (!user || !user.isActive || !user.hasCredit) return;
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  // Core logic is at the main level, clean and clear
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}

3. Magic Numbers Must Die#

Never write if (status === 2) directly in your code. Who knows what 2 means? Is it “Success”? “Failed”? Or “Processing”?

Refactor: Use enum or const constants.

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enum OrderStatus {
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  Pending = 0,
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  Processing = 1,
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  Completed = 2
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}
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if (order.status === OrderStatus.Completed) { ... }

4. Single Responsibility for Functions#

A function should only do one thing. If you find your function named fetchDataAndProcessAndSave(), it is definitely too long.

• Extract the “fetch data” logic.
• Extract the “process logic”.
• Extract the “save” logic. The main function should just act like a commander calling them.

5. Use Optional Chaining#

Bad:

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if (user && user.address && user.address.street) {
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  console.log(user.address.street);
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}

Good:

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console.log(user?.address?.street);

Not only is the code shorter, but the readability is also excellent.

Summary#

Good code is like a good article; it reads fluently. Refactoring is not about showing off, but about saving future you (and your colleagues) from losing a few strands of hair.