@rbxts/jsnatives

Number Constructor

The Number constructor creates a Number value.

Signature

function Number(value: unknown): number

Description

When called as a function, Number(value) converts the argument to a number. If the value cannot be converted, it returns NaN.

Parameters

value: The value to convert to a number.

Return value

A numeric value.

Examples

Basic Usage

// Converting string numbers
Number("123");       // 123
Number("123.45");    // 123.45
Number("");          // 0

// Number literals in different bases impossible, use parseInt instead
Number("0x11");      // 0 (hexadecimal)
Number("0b11");      // 0 (binary)
Number("0o11");      // 0 (octal)

// Invalid conversions
Number("foo");       // NaN
Number("100a");      // NaN

// Boolean conversions
Number(true);        // 1
Number(false);       // 0

// undefined
Number(undefined);   // NaN

Using for Type Conversion

// Converting user input to numbers
function processUserInput(input: string) {
  const numericValue = Number(input);

  if (Number.isNaN(numericValue)) {
    return "Please enter a valid number";
  }

  return `You entered: ${numericValue}`;
}

Formatting Before Conversion

// Clean a string before conversion
function parseCleanNumber(input: string): number {
  // Remove currency symbols, spaces, and other non-numeric characters
  const cleaned = input.replace(/[$,\s]/g, "");
  return Number(cleaned);
}

// Usage
parseCleanNumber("$1,234.56"); // 1234.56
parseCleanNumber("42 items");  // NaN (because "items" remains)

Checking Conversion Results

// Safe conversion with validation
function safeNumberConversion(value: unknown): number | null {
  const num = Number(value);

  if (Number.isNaN(num)) {
    return null;
  }

  return num;
}

// Usage
const validResult = safeNumberConversion("42");      // 42
const invalidResult = safeNumberConversion("hello"); // null

Combined with Other Number Methods

// Parse and format
function parseAndFormat(input: string, decimalPlaces = 2): string {
  const num = Number(input);

  if (Number.isNaN(num)) {
    return "Invalid number";
  }

  return Number.toFixed(num, decimalPlaces);
}

// Usage
parseAndFormat("123.456", 1);  // "123.5"
parseAndFormat("invalid");     // "Invalid number"