@rbxts/jsnatives


isFinite

Determines whether the passed value is a finite number.

Signature

function isFinite(value: number): boolean

Description

The Number.isFinite() method determines whether the passed value is a finite number - that is, it checks if the type of the value is Number and the value is neither positive Infinity, negative Infinity, nor NaN.

This is different from the global isFinite() function, which first coerces its argument to a number before testing it.

Parameters

Return value

Examples

Basic Usage

// Finite numbers
Number.isFinite(42);          // true
Number.isFinite(-42);         // true
Number.isFinite(42.5);        // true


// Non-finite numbers
Number.isFinite(Infinity);    // false
Number.isFinite(-Infinity);   // false
Number.isFinite(NaN);         // false


// Non-numbers
Number.isFinite("42");        // false
Number.isFinite(null);        // false
Number.isFinite(undefined);   // false

Validation Functions

// Validate that a value is usable for calculations
function isValidForMath(value: unknown): boolean {
  return Number.isFinite(Number(value));
}


// Test cases
isValidForMath(42);           // true
isValidForMath("42");         // true
isValidForMath(Infinity);     // false
isValidForMath("invalid");    // false

Preventing Division by Zero

// Safely divide two numbers
function safeDivide(a: number, b: number): number {
  // Check for division by zero or near-zero
  if (!Number.isFinite(a / b)) {
    throw new Error("Division by zero or resulting in a non-finite value");
  }


  return a / b;
}


// Usage
try {
  const result = safeDivide(10, 0);
} catch (error) {
  console.log(error.message); // "Division by zero or resulting in a non-finite value"
}

Range Checking in Graphics

// Check if a point is within the renderable area
function isPointRenderable(x: number, y: number): boolean {
  // Check that coordinates are finite numbers
  if (!Number.isFinite(x) || !Number.isFinite(y)) {
    return false;
  }


  // Additional bounds checking
  return x >= 0 && x < 1000 && y >= 0 && y < 800;
}

Filtering Arrays

// Filter out non-finite values from an array
function getFiniteValues(values: number[]): number[] {
  return values.filter(Number.isFinite);
}


// Usage
const mixedValues = [42, Infinity, -Infinity, NaN, 100];
const finiteOnly = getFiniteValues(mixedValues);
// finiteOnly is [42, 100]