parseInt vs Unary Plus: When Should You Choose Which Numeric Conversion Tool?

parseInt vs Unary Plus: Choosing the Right Numeric Conversion Tool

When working with strings that represent numbers in JavaScript, you can convert them to numeric values using two common methods: parseInt and the unary plus operator ( ). While both methods can yield the desired result, there are subtleties and performance differences that warrant careful consideration.

parseInt vs Unary Plus

parseInt takes two arguments: the string to be converted and the base (optional; defaults to 10). It interprets the string as an integer in the specified base and returns an integer if successful.

The unary plus operator, on the other hand, simply attempts to convert the operand to a number without specifying a base. If the operand is a valid numeric string, it returns the numeric value; otherwise, it returns NaN.

Performance

In general, the unary plus operator is noticeably faster than parseInt in Chrome. However, this performance difference may vary depending on the engine and version.

Error Handling

Both methods return NaN if the string cannot be converted to a number. However, parseInt has an additional feature that allows you to specify what to do if the string contains non-numeric characters. By default, it ignores them and converts the remaining numeric portion. You can override this behavior by providing a third argument specifying the position where the numeric portion begins.

Usage

Based on these differences, you should use parseInt when:

• You need to convert a string representation of an integer in a specific base.
• You want to handle non-numeric characters in a specific way.

Otherwise, you can use the unary plus operator for general numeric conversion, as it is typically faster and more convenient.

Comparison to the Double Tilde Operator (~~)

The double tilde operator (~~) coerces its operand to a 32-bit integer. It effectively removes the fractional part and performs bitwise negation, which has the effect of rounding down the number. Note that this operator does not consider the base of the input string.

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