← Loops over lists lesson New set →

App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 843 · 40 questions
TalentJR

Developer's tip (One by one): for (let i = 0; i < list.length; i++) visits every item, from position 0. Total: add each item. Count: add 1 when the test is true. Best: keep the biggest so far. The body runs once per item: a list of 5 runs it 5 times.

NameDateTime takenScore ___ / 40
  1. 1.🔁 What number does this code show?
    let scores = [82, 25, 97];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  2. 2.🔁 What does a loop do? (a) deletes code (b) draws icons (c) repeats code (d) saves photos
  3. 3.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 0, 1, 2, 3 (b) 1, 2, 3 (c) 0, 1, 2 (d) 3
  4. 4.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Zoya", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Zoya (b) Hi, Arjun (c) Hi, Meera
  5. 5.🔁 What number does this code show?
    let scores = [18, 14, 20, 20];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  6. 6.🔁 What number does this code show?
    let scores = [8, 10, 12, 20];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  7. 7.🔁 What number does this code show?
    let steps = [9, 14, 5, 17];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  8. 8.🔁 What number does this code show?
    let scores = [5, 1, 3];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  9. 9.🔁 What number does this code show?
    let runs = [9, 14, 6, 2];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  10. 10.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Aman", "Kabir", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Aman (c) Hi, Kabir (d) Hi, Zoya
  11. 11.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Meera", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Riya (c) Hi, Meera
  12. 12.🔁 What number does this code show?
    let steps = [13, 7, 3, 11, 19];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  13. 13.🔁 What number does this code show?
    let marks = [15, 1, 16, 17];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  14. 14.🔁 What number does this code show?
    let steps = [41, 33, 46];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  15. 15.🔁 What number does this code show?
    let scores = [17, 3, 9, 11];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  16. 16.🔁 What number does this code show?
    let marks = [10, 11, 12];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  17. 17.🔁 What number does this code show?
    let scores = [72, 87, 27];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  18. 18.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Kabir", "Zoya", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Aman (c) Hi, Arjun (d) Hi, Zoya
  19. 19.🔁 Why use a loop to show 100 messages? (a) it uses more lines (b) it hides them (c) it is slower (d) less code to write
  20. 20.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Riya", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Aman (c) Hi, Riya
  21. 21.🔁 What number does this code show?
    let runs = [26, 18, 10, 71, 73];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  22. 22.🔁 What number does this code show?
    let runs = [5, 1, 20, 7];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  23. 23.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Meera", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Riya (c) Hi, Meera
  24. 24.🔁 What number does this code show?
    let steps = [39, 40, 44, 28, 71];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  25. 25.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Riya", "Zoya", "Kabir", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Riya (c) Hi, Aman (d) Hi, Zoya
  26. 26.🔁 What number does this code show?
    let marks = [9, 14, 6];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  27. 27.🔁 What number does this code show?
    let marks = [11, 17, 19, 1];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  28. 28.🔁 What number does this code show?
    let scores = [16, 10, 9, 12];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  29. 29.🔁 What number does this code show?
    let scores = [77, 32, 49];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  30. 30.🔁 What number does this code show?
    let scores = [16, 19, 5, 14];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  31. 31.🔁 What number does this code show?
    let scores = [19, 7, 11, 7];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  32. 32.🔁 What number does this code show?
    let runs = [17, 17, 7, 16, 14];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  33. 33.🔁 What number does this code show?
    let marks = [9, 19, 8];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  34. 34.🔁 What number does this code show?
    let scores = [59, 44, 49];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  35. 35.🔁 What number does this code show?
    let scores = [17, 80, 69, 85];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  36. 36.🔁 What number does this code show?
    let runs = [4, 17, 10];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  37. 37.🔁 What number does this code show?
    let steps = [19, 11, 13];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  38. 38.🔁 What number does this code show?
    let marks = [10, 14, 16, 2, 18];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  39. 39.🔁 What number does this code show?
    let marks = [17, 6, 2, 17, 14];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  40. 40.🔁 What number does this code show?
    let scores = [38, 17, 63, 61, 23];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);

Answer key

  1. 2
  2. repeats code
  3. 0, 1, 2
  4. Hi, Arjun
  5. 20
  6. 50
  7. 45
  8. 5
  9. 31
  10. Hi, Zoya
  11. Hi, Arjun
  12. 19
  13. 49
  14. 0
  15. 17
  16. 33
  17. 2
  18. Hi, Arjun
  19. less code to write
  20. Hi, Aman
  21. 2
  22. 33
  23. Hi, Riya
  24. 1
  25. Hi, Arjun
  26. 14
  27. 19
  28. 47
  29. 2
  30. 54
  31. 44
  32. 71
  33. 19
  34. 3
  35. 3
  36. 31
  37. 19
  38. 60
  39. 17
  40. 2

Free app development lessons, practice and worksheets at talentjr.in/app-development-for-students