← Loops over lists lesson New set →

App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 504 · 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 steps = [1, 5, 20, 7];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  2. 2.🔁 What does a loop do? (a) deletes code (b) saves photos (c) repeats code (d) draws icons
  3. 3.🔁 What number does this code show?
    let scores = [7, 14, 19, 20, 2];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  4. 4.🔁 What number does this code show?
    let scores = [20, 8, 1, 3];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  5. 5.🔁 What number does this code show?
    let steps = [59, 47, 19, 54, 76];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  6. 6.🔁 Why use a loop to show 100 messages? (a) it uses more lines (b) it hides them (c) less code to write (d) it is slower
  7. 7.🔁 What number does this code show?
    let scores = [13, 10, 19, 19, 20];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  8. 8.🔁 What number does this code show?
    let runs = [98, 52, 91];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  9. 9.🔁 list.length tells you ___. (a) the last item (b) the biggest item (c) the first item (d) how many items it has
  10. 10.🔁 What number does this code show?
    let marks = [7, 12, 6, 17];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  11. 11.🔁 What number does this code show?
    let scores = [23, 28, 52];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  12. 12.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Riya", "Aman", "Meera", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Kabir (c) Hi, Riya (d) Hi, Zoya
  13. 13.🔁 A loop over a list of 5 items runs its body how many times? (a) 5 (b) 4 (c) 6 (d) 1
  14. 14.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Kabir", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Kabir (c) Hi, Aman
  15. 15.🔁 What number does this code show?
    let steps = [31, 54, 24, 77, 32];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  16. 16.🔁 What number does this code show?
    let runs = [6, 16, 4];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  17. 17.🔁 What number does this code show?
    let runs = [37, 35, 66, 20, 20];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  18. 18.🔁 What number does this code show?
    let marks = [15, 20, 1, 19];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  19. 19.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Arjun", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Aman (c) Hi, Zoya
  20. 20.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Zoya", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Zoya (c) Hi, Meera
  21. 21.🔁 What number does this code show?
    let steps = [3, 2, 10];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  22. 22.🔁 What number does this code show?
    let runs = [14, 6, 7];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  23. 23.🔁 What number does this code show?
    let scores = [91, 13, 91, 82, 35];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  24. 24.🔁 What number does this code show?
    let scores = [16, 4, 16, 15, 1];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  25. 25.🔁 What number does this code show?
    let marks = [30, 13, 42];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  26. 26.🔁 What number does this code show?
    let scores = [17, 15, 12];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  27. 27.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Riya", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Riya (c) Hi, Zoya
  28. 28.🔁 What number does this code show?
    let scores = [68, 64, 72];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  29. 29.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Riya", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Zoya (b) Hi, Riya (c) Hi, Arjun
  30. 30.🔁 What number does this code show?
    let steps = [85, 74, 35, 82];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  31. 31.🔁 What number does this code show?
    let runs = [16, 9, 2];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  32. 32.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 3 (b) 1, 2, 3 (c) 0, 1, 2 (d) 0, 1, 2, 3
  33. 33.🔁 What number does this code show?
    let scores = [9, 4, 5, 9, 14];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  34. 34.🔁 What number does this code show?
    let marks = [15, 16, 43];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  35. 35.🔁 What number does this code show?
    let steps = [2, 17, 6, 2];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  36. 36.🔁 What number does this code show?
    let scores = [90, 25, 65];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  37. 37.🔁 What number does this code show?
    let scores = [6, 1, 16, 10];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  38. 38.🔁 What number does this code show?
    let marks = [15, 15, 1, 10, 6];
    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 scores = [13, 18, 19];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  40. 40.🔁 What number does this code show?
    let steps = [11, 19, 4];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);

Answer key

  1. 33
  2. repeats code
  3. 62
  4. 20
  5. 4
  6. less code to write
  7. 81
  8. 3
  9. how many items it has
  10. 42
  11. 1
  12. Hi, Kabir
  13. 5
  14. Hi, Riya
  15. 1
  16. 26
  17. 1
  18. 55
  19. Hi, Zoya
  20. Hi, Meera
  21. 15
  22. 14
  23. 3
  24. 52
  25. 0
  26. 44
  27. Hi, Aman
  28. 3
  29. Hi, Zoya
  30. 3
  31. 16
  32. 0, 1, 2
  33. 14
  34. 1
  35. 17
  36. 2
  37. 16
  38. 47
  39. 19
  40. 34

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