When to Choose: parseInt, Unary Plus, or Double Tilde for String-to-Number Conversion?

parseInt vs Unary Plus: Understanding the Differences

Introduction

In JavaScript, we frequently encounter the need to convert strings into numbers. This poses a question: which method should we prefer for this conversion, parseInt or the unary plus operator ? This article explores the distinctions between the two approaches and provides guidance on when to employ each.

Comparison of parseInt and Unary Plus

Feature	parseInt	Unary Plus
Performance	Slower	Faster in current Chrome versions
Number Conversions	Accepts strings with leading and trailing whitespace, decimal points, and exponential notation	Accepts strings with leading whitespace, decimal points, and exponential notation
Non-Number Conversion	Returns NaN	Returns NaN
Casting to Integer	Parses strings as base-10 integers	Coerces strings to numbers

Use Cases

Based on the comparison, we can make informed decisions about when to use parseInt or the unary plus.

• Use parseInt:

  • When you need to parse a string as an integer, excluding leading whitespace and non-number characters.
  • When you're working with strings that may contain exponential notation or non-decimal numbers.

• Use Unary Plus:

  • When speed is a priority and the string contains only leading whitespace and no non-number characters.
  • When you're confident in the format of the input strings and don't require strict type checking.

Comparison with Double Tilde ~~ Operator

The double tilde operator ~~ is equivalent to the expression Math.floor(-x). It converts the value to its integer representation by removing all fractional digits. Unlike parseInt, it only accepts numbers and coerces non-numbers to NaN.

Conclusion

The choice between parseInt, unary plus, and double tilde depends on the specific requirements of your application. Consider factors such as precision, performance, and the expected format of the input strings.

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