When Should You Use `parseInt()` vs. `Number()` in JavaScript?

Distinguishing parseInt() from Number(): Unveiling the Semantic Differences

In JavaScript, parseInt() and Number() play pivotal roles in converting strings to numeric values. Despite their shared purpose, they exhibit distinct behaviors that warrant careful consideration.

Type Conversion vs. Parsing: Semantics Unraveled

Fundamentally, Number() serves as a constructor that performs type conversion, casting the provided string into a number. parseInt(), on the other hand, undertakes parsing, diligently extracting numeric content from the string.

Numeric Extraction in Different Contexts

These semantic differences manifest in tangible results. Observe the following examples:

• Parsing:

  • parseInt("20px") // 20
  • parseInt("10100", 2) // 20 (binary conversion)
  • parseInt("2e1") // 2

• Type Conversion:

  • Number("20px") // NaN (invalid number)
  • Number("2e1") // 20 (exponential notation)

Trailing Characters and Number Detection

parseInt() exhibits an additional nuance: it disregards trailing characters that do not constitute digits in the specified base.

Octal and Hexadecimal: Navigating Number Bases

Unlike Number(), parseInt() can inherently detect implicit octal notation. Additionally, both functions handle hexadecimal notation seamlessly:

• Number("0o10") // 8 (explicit octal)
• parseInt("010") // 8 (implicit octal)
• Number("0xF") // 15
• parseInt("0xF") // 15

Unifying the Conversion Approach: Unary Plus Operator

The Unary Plus Operator ( ) provides a versatile alternative for numeric type conversion, effectively mirroring the behavior of Number():

• "2e1" // 20
• "0xF" // 15
• "010" // 10

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