Why Does JavaScript’s parseInt(0.0000005) Print “5”? 🤔

Why Does JavaScript’s parseInt(0.0000005) Print “5”? 🤔

JavaScript’s parseInt() function is quite handy for converting strings into integers, but it can sometimes lead to surprising results. One such mystery is when you call:

parseInt(0.0000005)

And the output is 5! 😲

The Reason Behind It

Here’s the simple explanation: parseInt() doesn't just look at the number itself. It first converts the value to a string. So, when we pass 0.0000005, JavaScript automatically converts it to the string "5e-7". 🎢

Now, parseInt() starts reading the string from the left and stops at the first non-numeric character. In "5e-7", it sees 5 first, so it stops there and returns 5. It doesn’t process the scientific notation part (e-7), which is why it ignores the decimals.

Summary 📜

• 
  parseInt() processes numbers as strings.


• It only reads up to the first non-numeric character.


• The result is the integer before the first non-digit character.

Final Trick Question! 🧩

What will console.log(0.1 + 0.2 == 0.3) return? 🤨 Try it and see if you can crack this JavaScript mystery!