💡 JavaScript Conditional Statements Practice Exercises

Write a function that checks whether a number is positive, negative, or zero.

function checkNumber(num) {
          if (num > 0) {
            return "Positive";
          } else if (num < 0) {
            return "Negative";
          } else {
            return "Zero";
          }
        }

Write a function that determines if a given number is even or odd.

function isEvenOrOdd(num) {
          if (num % 2 === 0) {
            return "Even";
          } else {
            return "Odd";
          }
        }

Write a function that checks if a person is eligible to vote based on age. A person is eligible if their age is 18 or above.

function canVote(age) {
          if (age >= 18) {
            return "Eligible to vote";
          } else {
            return "Not eligible to vote";
          }
        }

Create a function that calculates a letter grade based on a numerical score:

• 90-100: 'A'
• 80-89: 'B'
• 70-79: 'C'
• 60-69: 'D'
• Below 60: 'F'

Implement this using both if/else if and switch statements.

// If/else if version
        function calculateGradeIfElse(score) {
          if (score >= 90 && score <= 100) return 'A';
          else if (score >= 80) return 'B';
          else if (score >= 70) return 'C';
          else if (score >= 60) return 'D';
          else if (score >= 0) return 'F';
          else return 'Invalid score';
        }
        
        // Switch version
        function calculateGradeSwitch(score) {
          const gradeRange = Math.floor(score / 10);
          switch (gradeRange) {
            case 10:
            case 9: return 'A';
            case 8: return 'B';
            case 7: return 'C';
            case 6: return 'D';
            case 5:
            case 4:
            case 3:
            case 2:
            case 1:
            case 0: return 'F';
            default: return 'Invalid score';
          }
        }

Create a function that takes a day number (1-7) and returns a custom message for each day of the week:

• 1: Monday – "Start of the work week"
• 2: Tuesday – "Taco Tuesday!"
• 3: Wednesday – "Halfway there!"
• 4: Thursday – "Almost the weekend"
• 5: Friday – "TGIF!"
• 6: Saturday – "Weekend fun day"
• 7: Sunday – "Rest day"

Implement this using both if/else if and switch statements.

// If/else if version
        function getDayMessageIfElse(dayNumber) {
          if (dayNumber === 1) return "Start of the work week";
          else if (dayNumber === 2) return "Taco Tuesday!";
          else if (dayNumber === 3) return "Halfway there!";
          else if (dayNumber === 4) return "Almost the weekend";
          else if (dayNumber === 5) return "TGIF!";
          else if (dayNumber === 6) return "Weekend fun day";
          else if (dayNumber === 7) return "Rest day";
          else return "Invalid day number";
        }
        
        // Switch version
        function getDayMessageSwitch(dayNumber) {
          switch (dayNumber) {
            case 1: return "Start of the work week";
            case 2: return "Taco Tuesday!";
            case 3: return "Halfway there!";
            case 4: return "Almost the weekend";
            case 5: return "TGIF!";
            case 6: return "Weekend fun day";
            case 7: return "Rest day";
            default: return "Invalid day number";
          }
        }

Create a function called calculateDiscount that determines the discount a customer receives based on their total purchase amount:

• Purchases under $50: No discount
• Purchases between $50 and $100: 5% discount
• Purchases between $100 and $200: 10% discount
• Purchases over $200: 15% discount

Then, write both if/else if and switch versions of this function.

// If/else if version
        function calculateDiscountIfElse(totalAmount) {
          if (totalAmount < 50) return 0;
          else if (totalAmount < 100) return totalAmount * 0.05;
          else if (totalAmount < 200) return totalAmount * 0.10;
          else return totalAmount * 0.15;
        }
        
        // Switch version
        function calculateDiscountSwitch(totalAmount) {
          const range = Math.floor(totalAmount / 50);
          switch (range) {
            case 0: return 0;
            case 1: return totalAmount * 0.05;
            case 2:
            case 3: return totalAmount * 0.10;
            default: return totalAmount * 0.15;
          }
        }

Create a function that calculates shipping cost based on:

• Package weight (in pounds)
• Shipping distance (in miles)
• Shipping speed (standard, express, or overnight)

Rules:

• Weight under 1lb: $1.50 per pound
• Weight 1-5lb: $3.00 per pound
• Weight over 5lb: $4.50 per pound
• Distance under 100 miles: No additional charge
• Distance 100-500 miles: $5 additional
• Distance over 500 miles: $10 additional
• Standard shipping: No additional charge
• Express shipping: $12 additional
• Overnight shipping: $25 additional

function calculateShippingCost(weight, distance, speed) {
          let cost = 0;
          if (weight < 1) cost += weight * 1.50;
          else if (weight <= 5) cost += weight * 3.00;
          else cost += weight * 4.50;
        
          if (distance >= 100 && distance <= 500) cost += 5;
          else if (distance > 500) cost += 10;
        
          switch (speed.toLowerCase()) {
            case "standard": break;
            case "express": cost += 12; break;
            case "overnight": cost += 25; break;
            default: return "Invalid shipping speed";
          }
        
          return cost.toFixed(2);
        }