← Loops over lists lesson New set →

App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 405 · 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.🔁 list.length tells you ___. (a) the first item (b) how many items it has (c) the last item (d) the biggest item
  2. 2.🔁 What number does this code show?
    let marks = [15, 8, 7];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  3. 3.🔁 What does a loop do? (a) draws icons (b) deletes code (c) repeats code (d) saves photos
  4. 4.🔁 What number does this code show?
    let marks = [7, 20, 4, 12];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  5. 5.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 1, 2, 3 (b) 0, 1, 2 (c) 3 (d) 0, 1, 2, 3
  6. 6.🔁 What number does this code show?
    let marks = [20, 5, 3];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  7. 7.🔁 What number does this code show?
    let marks = [7, 18, 1, 19];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  8. 8.🔁 What number does this code show?
    let runs = [6, 1, 3, 1, 12];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  9. 9.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Aman", "Arjun", "Zoya", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Meera (c) Hi, Aman (d) Hi, Arjun
  10. 10.🔁 What number does this code show?
    let runs = [1, 3, 6];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  11. 11.🔁 What number does this code show?
    let marks = [14, 14, 16];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  12. 12.🔁 What number does this code show?
    let marks = [2, 2, 3];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  13. 13.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Kabir", "Aman", "Zoya", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Kabir (c) Hi, Riya (d) Hi, Aman
  14. 14.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Aman", "Zoya", "Arjun", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Meera (c) Hi, Zoya (d) Hi, Aman
  15. 15.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Aman", "Kabir", "Zoya", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Kabir (c) Hi, Riya (d) Hi, Arjun
  16. 16.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Arjun", "Riya", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Zoya (c) Hi, Riya (d) Hi, Meera
  17. 17.🔁 What number does this code show?
    let marks = [14, 18, 5];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  18. 18.🔁 What number does this code show?
    let scores = [11, 95, 78];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  19. 19.🔁 What number does this code show?
    let steps = [26, 45, 24, 27, 98];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  20. 20.🔁 A loop over a list of 5 items runs its body how many times? (a) 5 (b) 4 (c) 1 (d) 6
  21. 21.🔁 What number does this code show?
    let runs = [10, 85, 49];
    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 marks = [10, 8, 7, 6, 4];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  23. 23.🔁 What number does this code show?
    let runs = [4, 17, 15, 15];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  24. 24.🔁 Why use a loop to show 100 messages? (a) less code to write (b) it hides them (c) it is slower (d) it uses more lines
  25. 25.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Meera", "Arjun", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Kabir (c) Hi, Meera (d) Hi, Aman
  26. 26.🔁 What number does this code show?
    let scores = [15, 7, 12, 4, 18];
    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 = ["Kabir", "Aman", "Zoya", "Riya", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Aman (c) Hi, Zoya (d) Hi, Arjun
  28. 28.🔁 What number does this code show?
    let steps = [58, 15, 56, 72, 10];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  29. 29.🔁 What number does this code show?
    let scores = [19, 18, 15];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  30. 30.🔁 What number does this code show?
    let scores = [86, 45, 64, 44, 77];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  31. 31.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Aman", "Riya", "Arjun", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Aman (c) Hi, Zoya (d) Hi, Kabir
  32. 32.🔁 What number does this code show?
    let scores = [20, 45, 17, 50, 80];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  33. 33.🔁 What number does this code show?
    let marks = [20, 5, 1, 2];
    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 = [15, 9, 17];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  35. 35.🔁 What number does this code show?
    let steps = [14, 8, 19];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  36. 36.🔁 What number does this code show?
    let runs = [48, 51, 78, 17, 28];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  37. 37.🔁 What number does this code show?
    let steps = [55, 80, 72, 19, 31];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  38. 38.🔁 What number does this code show?
    let runs = [17, 15, 13];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  39. 39.🔁 What number does this code show?
    let marks = [16, 19, 13];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  40. 40.🔁 What number does this code show?
    let steps = [11, 10, 19, 9, 18];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);

Answer key

  1. how many items it has
  2. 30
  3. repeats code
  4. 43
  5. 0, 1, 2
  6. 20
  7. 45
  8. 12
  9. Hi, Meera
  10. 10
  11. 44
  12. 7
  13. Hi, Riya
  14. Hi, Kabir
  15. Hi, Arjun
  16. Hi, Zoya
  17. 37
  18. 2
  19. 1
  20. 5
  21. 1
  22. 10
  23. 51
  24. less code to write
  25. Hi, Aman
  26. 56
  27. Hi, Arjun
  28. 3
  29. 19
  30. 3
  31. Hi, Kabir
  32. 1
  33. 20
  34. 41
  35. 41
  36. 1
  37. 3
  38. 45
  39. 48
  40. 19

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