JavaScript provides the parseInt function to convert strings into integers. However, it has some nuances that developers must understand to use it effectively.

Syntax of parseInt

parseInt(string, radix);

• string: The value to be converted.

• radix: The base of the numerical system (optional but highly recommended).

Example 1: Basic Usage

console.log(parseInt("42")); // Output: 42
console.log(parseInt("0037")); // Output: 37

Example 2: Using Radix

console.log(parseInt("10", 2));  // Output: 2 (Binary to Decimal)
console.log(parseInt("A", 16));  // Output: 10 (Hexadecimal to Decimal

Why Specifying Radix is Important

If the radix is not specified, JavaScript may misinterpret the number:

console.log(parseInt("08"));  // Output: 8 (Modern JS assumes decimal)
console.log(parseInt("08", 10));  // Output: 8 (Explicitly decimal)

Handling Non-Numeric Values

parseInt stops parsing at the first non-numeric character:

console.log(parseInt("123abc")); // Output: 123
console.log(parseInt("abc123")); // Output: NaN (Not a Number)

Common Mistakes

1. Not specifying the radix

2. Assuming parseInt rounds numbers

console.log(parseInt("10.9")); // Output: 10 (It truncates, not rounds)

Conclusion

parseInt is a useful function in JavaScript but requires careful handling, especially with radix. Always specify the radix to avoid unexpected results!

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