The Hidden Truth Behind null >= 0 and Other JS Logic Traps

🧠 Why null >= 0 is true and other JavaScript WTFs 🤯

If you've ever seen a JavaScript comparison and thought,

"Okay... that's just broken."
You're not wrong.

JavaScript’s type coercion plays by its own set of rules — and they’re not always obvious.

Let’s walk through some lesser-known but equally quirky comparisons — and break them down, step by step.

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🧪 Example 1: null >= 0 // true

Wait, what?!
null is not equal to 0, but it's greater than or equal to it?

Let’s break it down:

null >= 0

Step-by-step:

1. The relational comparison >= triggers numeric coercion.

2. null becomes 0

3. So it becomes:

    0 >= 0 // true
   

   👉 Final result: true

Wild.

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🧪 Example 2: null > 0 // false

Here’s the twist:

null > 0 // false

Still using numeric coercion:

Number(null) > 0
0 > 0 // false

👉 Final result: false

Same coercion rule, but now it's a strict "greater than."

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🧪 Example 3: null == 0 // false

This one feels inconsistent:

null == 0 // false

Why?

Because == uses different coercion logic than < or >=.

null only loosely equals undefined — not numbers, booleans, or strings.

👉 Final result: false

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🧪 Example 4: undefined >= 0 // false

undefined >= 0 // false

Let’s walk through it:

1. undefined coerces to NaN

2. Comparing NaN >= 0 → always false

👉 Final result: false

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🧪 Bonus Round: [null] == 0 // true

You didn’t ask, but here’s another curveball:

[null] == 0 // true

How?

1. [null] → '' (empty string after flattening)

2. '' == 0 → true (because Number('') → 0)

👉 Final result: true

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🎯 TL;DR — What to Remember

• == and >= use different coercion rules

• null becomes 0 in numeric comparisons (>=, >, etc.)

• null only equals undefined with ==, not anything else

• undefined turns into NaN in numeric operations

• Arrays get coerced to strings or numbers based on context

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💡 Pro Tip:

If it feels broken… it probably is — but there’s logic behind the madness.
When in doubt, break it down like the engine does: coercion → comparison.

Or better yet:

Use === and avoid this rabbit hole altogether.

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💬 Bonus:

What’s your favorite WTF comparison in JavaScript?

👇 Drop it in the comments!

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