← Loops over lists lesson New set →

App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 852 · 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.🔁 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
  2. 2.🔁 A loop over a list of 5 items runs its body how many times? (a) 6 (b) 1 (c) 4 (d) 5
  3. 3.🔁 What number does this code show?
    let runs = [13, 3, 18, 3, 7];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  4. 4.🔁 What number does this code show?
    let runs = [13, 1, 6];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  5. 5.🔁 What number does this code show?
    let marks = [6, 18, 1, 5];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  6. 6.🔁 What number does this code show?
    let scores = [30, 99, 12, 30, 42];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  7. 7.🔁 Why use a loop to show 100 messages? (a) it is slower (b) it hides them (c) it uses more lines (d) less code to write
  8. 8.🔁 What number does this code show?
    let steps = [17, 13, 81, 27, 66];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  9. 9.🔁 What number does this code show?
    let runs = [3, 9, 9];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  10. 10.🔁 What does a loop do? (a) repeats code (b) deletes code (c) saves photos (d) draws icons
  11. 11.🔁 What number does this code show?
    let steps = [12, 14, 1, 9];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  12. 12.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Zoya", "Meera", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Zoya (b) Hi, Arjun (c) Hi, Meera (d) Hi, Riya
  13. 13.🔁 What number does this code show?
    let marks = [4, 16, 16, 10];
    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 marks = [50, 25, 89, 82, 81];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  15. 15.🔁 What number does this code show?
    let runs = [20, 14, 3];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  16. 16.🔁 What number does this code show?
    let marks = [5, 5, 19, 12];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  17. 17.🔁 What number does this code show?
    let steps = [8, 19, 1, 7];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  18. 18.🔁 What number does this code show?
    let runs = [3, 2, 4, 12, 6];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  19. 19.🔁 What number does this code show?
    let runs = [9, 7, 8];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  20. 20.🔁 What number does this code show?
    let marks = [67, 79, 47, 50, 21];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  21. 21.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Aman", "Meera", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Aman (c) Hi, Meera (d) Hi, Riya
  22. 22.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Meera", "Arjun", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Meera (c) Hi, Arjun (d) Hi, Zoya
  23. 23.🔁 What number does this code show?
    let scores = [14, 20, 9, 20, 15];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  24. 24.🔁 What number does this code show?
    let marks = [73, 43, 37, 18, 44];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  25. 25.🔁 What number does this code show?
    let runs = [3, 17, 12];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  26. 26.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Riya", "Meera", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Riya (c) Hi, Aman (d) Hi, Meera
  27. 27.🔁 list.length tells you ___. (a) how many items it has (b) the biggest item (c) the first item (d) the last item
  28. 28.🔁 What number does this code show?
    let marks = [20, 3, 12];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  29. 29.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Kabir", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Zoya (b) Hi, Kabir (c) Hi, Aman
  30. 30.🔁 What number does this code show?
    let steps = [44, 79, 22, 77];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  31. 31.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Riya", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Riya (c) Hi, Zoya
  32. 32.🔁 What number does this code show?
    let marks = [13, 5, 15, 3, 14];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  33. 33.🔁 What number does this code show?
    let scores = [13, 16, 10, 18];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  34. 34.🔁 What number does this code show?
    let runs = [18, 43, 60];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  35. 35.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Aman", "Zoya", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Zoya (c) Hi, Arjun (d) Hi, Aman
  36. 36.🔁 What number does this code show?
    let runs = [19, 28, 99];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  37. 37.🔁 What number does this code show?
    let runs = [17, 3, 3, 17];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  38. 38.🔁 What number does this code show?
    let scores = [9, 4, 4, 19];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  39. 39.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Meera", "Riya", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Arjun (c) Hi, Meera (d) Hi, Riya
  40. 40.🔁 What number does this code show?
    let steps = [10, 4, 19, 2];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);

Answer key

  1. 0, 1, 2
  2. 5
  3. 44
  4. 13
  5. 30
  6. 1
  7. less code to write
  8. 2
  9. 21
  10. repeats code
  11. 14
  12. Hi, Riya
  13. 46
  14. 4
  15. 37
  16. 19
  17. 35
  18. 27
  19. 24
  20. 4
  21. Hi, Riya
  22. Hi, Zoya
  23. 78
  24. 1
  25. 32
  26. Hi, Aman
  27. how many items it has
  28. 35
  29. Hi, Aman
  30. 2
  31. Hi, Zoya
  32. 50
  33. 57
  34. 1
  35. Hi, Kabir
  36. 1
  37. 17
  38. 19
  39. Hi, Arjun
  40. 35

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