Why Does JavaScript's `parseInt` Treat Leading Zeros as Octal, and How Can I Fix It?

JavaScript's Intriguing Octal Behavior: Understanding and Circumventing It

When working with JavaScript, you might encounter a peculiar behavior that can lead to confusion. The parseInt function, when presented with numbers prefixed with a leading zero, interprets them as octal integers. This means that for values greater than 7 in an octal representation, the function returns zero.

For example:

parseInt('01'); // equals 1
parseInt('02'); // equals 2
parseInt('03'); // equals 3
parseInt('04'); // equals 4
parseInt('05'); // equals 5
parseInt('06'); // equals 6
parseInt('07'); // equals 7
parseInt('08'); // equals 0 !!
parseInt('09'); // equals 0 !!

To resolve this issue and ensure that parseInt behaves as expected, there are a few workarounds:

1. Specify the Base (Radix):
   You can explicitly specify the base or radix when using parseInt. For instance, to interpret a number as a decimal integer, you can use the following syntax:

   parseInt('08', 10); // returns 8

2. Use the Number Object:
   Alternatively, you can use the Number object instead of parseInt. The Number object automatically interprets numbers without a leading zero as decimal integers:

   Number('08'); // returns 8

By understanding and employing these workarounds, you can effectively overcome JavaScript's octal behavior and ensure accurate integer parsing.

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