2-is-proper-fraction.js

// Implement a function isProperFraction,
// when given two numbers, a numerator and a denominator, it should return true if
// the given numbers form a proper fraction, and false otherwise.

// Assumption: The parameters are valid numbers (not NaN or Infinity).

// Note: If you are unfamiliar with proper fractions, please look up its mathematical definition.

// Acceptance criteria:
// After you have implemented the function, write tests to cover all the cases, and
// execute the code to ensure all tests pass.

function isProperFraction(numerator, denominator) {
  return Math.abs(numerator) < Math.abs(denominator) ? true : false;
}

// The line below allows us to load the isProperFraction function into tests in other files.
// This will be useful in the "rewrite tests with jest" step.
module.exports = isProperFraction;

// Here's our helper again
function assertEquals(actualOutput, targetOutput) {
  console.assert(
    actualOutput === targetOutput,
    `Expected ${actualOutput} to equal ${targetOutput}`
  );
}

// Acceptance criteria:

// Proper Fraction check:
// Input: numerator = 2, denominator = 3
// target output: true
// Explanation: The fraction 2/3 is a proper fraction, where the numerator is less than the denominator. The function should return true.
const properFraction = isProperFraction(2, 3);
assertEquals(properFraction, true);

// Improper Fraction check:
// Input: numerator = 5, denominator = 2
// target output: false
// Explanation: The fraction 5/2 is an improper fraction, where the numerator is greater than or equal to the denominator. The function should return false.
const improperFraction = isProperFraction(5, 2);
assertEquals(improperFraction, false);

// Negative Fraction check:
// Input: numerator = -4, denominator = 7
// target output: true
// Explanation: The fraction -4/7 is a proper fraction because the absolute value of the numerator (4) is less than the denominator (7). The function should return true.
const negativeFraction = isProperFraction(-4, 7);
// ====> complete with your assertion
assertEquals(negativeFraction, true);

// Equal Numerator and Denominator check:
// Input: numerator = 3, denominator = 3
// target output: false
// Explanation: The fraction 3/3 is not a proper fraction because the numerator is equal to the denominator. The function should return false.
const equalFraction = isProperFraction(3, 3);
// ====> complete with your assertion
assertEquals(equalFraction, false);

// Stretch:
// What other scenarios could you test for?

// Zero Numerator check:
// Input: numerator = 0, denominator = 5
// target output: true
// Explanation: The fraction 0/5 is a proper fraction because the numerator is less than the denominator.
const zeroNumerator = isProperFraction(0, 5);
assertEquals(zeroNumerator, true);

// Zero Denominator check:
// Input: numerator = 5, denominator = 0
// target output: false
// Explanation: The fraction 5/0 is undefined because division by zero is not allowed.
const zeroDenominator = isProperFraction(5, 0);
assertEquals(zeroDenominator, false);