1 Answer Unit 7,81 Answer Unit 7,81 Answer Unit 7,81 Answer Unit 7,81 Answer Unit 7,8

Q1: which of the following identifiers represents an invalid variable name, and why?myNumber

my.Number

my-Number

my_Number

my Number

$myNumber

myNumber2

8myNumber

While

Q2: Write a JavaScript code to declare a variable called myNumber; initialize it with the number 7; add 3 to its value; and finally display the new value. (M150A final exam, Fall 2008)var myNumber;myNumber = 7;myNumber = myNumber + 3;document.write('The new value of myNumber is ' + myNumber);

Q3: Write a JavaScript code to do the following: Ask the user to enter his / her name Display on the screen: Welcome followed by the user namevar userName;

userName = window.prompt('Please enter your name','');

document.write('Welcome ' + userName);

Q4: Write a JavaScript code to compute and print the perimeter of a rectangle as follows: Ask the user to enter the length and width of the rectangle Compute the perimeter of the rectangle based on the formula:Perimeter = 2 (length + width) Print the computed perimeter in the output windowvar length, width, perimeter;length = window.prompt('Please enter the rectangle length','');length = parseFloat(length);width = window.prompt('Please enter the rectangle width','');width = parseFloat(width);perimeter = 2 * (length + width);document.write('The rectangle perimeter is ' + perimeter)

Q5: Write an equivalent JavaScript code to the following flow chart:

var grade;

grade = window.prompt('Please enter the grade','');grade = parseFloat(grade);

if (grade >= 90)

{document.write("Excellent");}else{document.write("Done");}

Q6: Write a JavaScript code to identify if a student passes specific course or failedBased on his final score according to the following: Read the final score from the user. If the final score is greater than or equal to 50, print on the screen Passed, otherwise print Failed.var score;

score = window.prompt('Please enter your score','');score = parseFloat(score);

if (score >= 50)

{document.write("Passed");}else{document.write("Failed");}


var grade;


if (grade < 50)

{document.write('Failed' + '
' + 'Finished');}else{document.write('Passed' + '
' + 'Finished');}

Q8: Write a JavaScript code to identify if a student passes a specific course or failed based on his final score according to the following: Read the final score from the user Check the score, if it is less than 0 or greater than 100, print Invalid Score on the output screen, otherwise complete as follows: If the final score is greater than or equal to 50, print on the screen Passed, otherwise print Failedvar score;

score = window.prompt('Please enter your score','');score = parseFloat(score);

if (score < 0 || score > 100)

{document.write("Invalid Score");}else{if (score >= 50){document.write("Passed");}else{document.write("Failed");}}

Q9: Write a JavaScript code that will assign a grade to a student, based on his final score according to the following table:Score rangeGrade

90 - 100A

80 89B

70 79C

50 69D

0 49F

The program works as follows: Read the students final score. (Assume that the user will insert a score between 0 and 100) Assign the grade to the student according to the above table. Print the grade in the output window.var score, grade;score = window.prompt('Enter your score','');score = parseFloat(score);if (score >= 90){grade = 'A'}else{if (score >= 80){grade = 'B'}else{if (score >= 70){grade = 'C'}else{if (score >= 50){grade = 'D'}else{grade = 'F'}}}}document.write('The grade of ' + score + ' is ' + grade)


document.write('Hello' + '
');

var grade;


if (grade < 0 || grade > 100)

{document.write('The grade is not correct');}else{if (grade >= 50){document.write('Passed');}else{document.write('Sorry ' + 'Failed');}}document.write('
' + 'Thank you')

Q11: Trace the following JavaScript code giving the exact output:var x, y;y = 7;x = 1 + 4 + 8;document.write('First, x = ' + x + ' and y = ' + y);document.write('
');

x = y + 2;x = x + 6;x = 3 + x / 3;document.write("Now, x = " + x + 'and y = ' + y + "
");

x = y;y = 9;// y = y + 10;document.write("Finally, x = " + x + "and y = " + y);

Answer: First, x = 13 and y = 7Now, x = 8and y = 7Finally, x = 7and y = 9

Q12: Trace the following JavaScript code giving the exact output:var w, y, z, text1, text2, text3, text4;w = '12'; x = '5';y = 12; z = 5;text1 = "CAR"; text2 = "car";text3 = "cat"; text4 = "cairo";

if ((w < x) && (y > z))document.write("First" + "
");elsedocument.write("Second" + "
");document.write("Guess" + "
");if ((text1 == text2) || (text3 < text4))document.write("Third" + "
");elsedocument.write("Fourth" + "
");if ((z != 10) && (text2 < text3)){z = z * 10;document.write("Finally, it is a " + text2);document.write(" for " + y + z);}else{z = z * 10;document.write("See you");}document.write("
" + "The End - " + "text4");

Answer: FirstGuessFourthFinally, it is a car for 1250The End - text4

Q13: The following JavaScript code has some errors. Identify the errors and rewrite the code correctly.var my Value;if (myValue = 0window.write("OK");

var myValue;myValue = window.prompt('Please enter the value','');myValue = parseFloat(myValue);

if (myValue == 0){document.write("OK")};

Q14: The following JavaScript code has some errors and a missing statement. Identify the errors and rewrite the code correctly.var mark;bar bonus = 2;mark = window.pompt('Insert the student mark','');mark = mark + bonus;if mark >= 50document.write('Passed);Elsedocument.write('Failed');

var mark;var bonus = 0;mark = window.prompt('Insert the student mark','');mark = parseFloat(mark);mark = mark + bonus;if (mark >= 50){document.write('Passed');}else{document.write('Failed');}

Q15: Trace out the following JavaScript code and state how many different paths it has, showing a possible output of each path and discussing briefly the purpose of the two if-else statements included.var num1, num2, oper, result;

num1 = parseFloat(window.prompt('Enter the 1st number:',''));num2 = parseFloat(window.prompt('Enter the 2st number:',''));

oper = window.prompt('Enter the operator: (+ or -)','');if((oper == '+') || (oper == '-')){if (oper == '+'){result = num1 + num2;document.write(num1 + oper + num2 + '=' + result);}else{result = num1 - num2;document.write(num1 + oper + num2 + '=' + result);}}else{document.write('Invalid operator');}

Answer Q15: The given code has 3 different paths.1. For invalid operator rather than + or -, it will printout Invalid operator message.2. For + operator, it will printout the output of adding the two variables num1 and num2. For example if the user entered 5 and 7. The output message would be 5 + 7 = 12.3. For operator, it will printout the output so subtracting the variable num2 from num1. For example if the user entered 10 and 3, the output message would be 10 -3 = 7.

Q16: Trace the following code then answer the questions below:var x, y;x = 10;y = 0;while(x >= 6){x = x - 2;y = y + x;}

a. How many times will the loop be executed?3 times.b. What are the values of x and y after the execution of the above code?x = 4, y =18c. What do you expect to happen if the initial value of x was 5 instead of 10?If the initial value of x was 5 instead of 10, the condition (x >= 6) will evaluate false and the loop body will not evaluated at all. Hence, the values of x and y remain the same.Q17: Trace the following code then answer the questions below:var x, y;x = 1; y = 1;while (x != 7){y = y * x;x = x + 2;}

a. How many times will the loop be executed?3 times.b. What are the values of x and y after the execution of the above code?x = 7, y = 15c. What do you expect to happen if the initial value of x was 2 instead of 1?If the initial value of x was 2 instead of 1 it will be an infinite loop. This is because the value of x will be added by resulting 2, 4, 6, 8, 10, and thus the condition (x != 7) will never be false.

Q18: Given the following code: (M150A final exam, Fall 2009)for(var i = 0; i < 10; i++){document.write(i);}

a. What is the output?0123456789b. How would you modify the code so that it prints the numbers backwards?for (i = 9; i >= 0; i--){document.write(i);}

c. How would you modify the code so that it prints only the even numbers?for (i = 0; i < 10; i++){if (i % 2 == 0)document.write(i);}

or

for (i = 0; i < 10; i = i + 2){document.write(i);}

d. How would you modify the code so that it sums all the values of i and prints the final sum?var sum;sum = 0;for (i = 0; i < 10; i++){sum = sum + i;}document.write("final sum is " + sum);

Q19: Write a JavaScript program to print a table of consecutive even numbers from 2 to 30 and their square values.A sample output of this is as follows:24

416

636

28784

30900

for(var i = 2; i = 0; count = count - 1){document.write(string1.charAt(count));

}

Q26: Write a JavaScript code that takes a string from the user and outputs the number of vowels in that string. (M150A final exam, Fall 2009)[vowels are the letter a, e, i, o, u]var myString, counter = 0, ch;myString = window.prompt('Please enter a string','');for (i = 0; i < myString.length; i = i + 1){ch = myString.charAt(i);if (ch == 'a' || ch == 'A' || ch == 'e' || ch == 'E' || ch == 'i' || ch == 'I' ||ch == 'o' || ch == 'O' || ch == 'u' || ch == 'U'){counter = counter + 1;}}document.write('The are ' + counter + ' vowels in the string');

Q27: What is the value of y after the execution of the following java script code?You are required to show how you have obtained the result. (M150A final exam, Fall 2009)var x = 4;var y = x + 2;var count = 1;while (count < x){y = y * 2;count = count + 1;}

Answer: 48

Q28: Write JavaScript code to calculate and print the area of a triangle as follows: Ask the user to enter the base and the height of the triangle. Calculate the area of the triangle based on the formula:area = 1 / 2 * (base * height) Print the calculated area in the output window.var base, height, area;base = window.prompt('Please enter the triangle base','');base = parseFloat(base);height = window.prompt('Please enter the triangle height','');height = parseFloat(height);area = 1 / 2 * (base * height);document.write('The triangle area is ' + area)

Q29: Using the while loop, write JavaScript code to do the following:a. Print the numbers from 1 to 20.var i = 1;while (i = 1){document.write(i);i = i - 1;}

c. Modify the code so that it prints only the even number from 1 to 20.var i = 2;while (i max){max = anArray[i];}}return max;};function calcMin(anArray){var min = anArray[0];for( i = 1; i < (anArray.length); i = i + 1){if(anArray[i] < min){min = anArray[i];}}return min;};function calcPositive(anArray){var positives = 0;for(i = 0; i < (anArray.length);i = i + 1){if(anArray[i] > 0){positives = positives + 1;}}return positives;};function calcNegative(anArray){var negatives = 0;for(i = 0; i < (anArray.length); i = i + 1){if(anArray[i] < 0){negatives = negatives + 1;}}return negatives;};function calcZero(anArray){var zeroes = 0;for(i = 0; i < (anArray.length); i = i + 1){if(anArray[i] == 0){zeroes = zeroes + 1;}}return zeroes;};function displayInfo(anArray){document.write('myArray has the following elements: ' + anArray + '
');document.write('The max value = ' + calcMax(anArray) + '
');document.write('The min value = ' + calcMin(anArray) + '
');document.write('The number of positive values = ' + calcPositive(anArray) + '
');document.write('The number of negative values = ' + calcNegative(anArray) + '
');document.write('The number of zero values = ' + calcZero(anArray) + '
');};var myArray = [2, 0, 1, -4, 10, 3, -2, 0, 3, 5];displayInfo(myArray);

Q36:

var ourNumber, userNumber, count;ourNumber = 501;userNumber = window.prompt('Enter a number between 1 and 1000', '');userNumber = parseFloat(userNumber);count = 1;while ( ourNumber != userNumber){if (ourNumber < userNumber){window.alert('You are above the right number!');}else{window.alert('You are below the right number!');}userNumber = window.prompt('Try again :', '');userNumber = parseFloat(userNumber);count = count + 1;}document.write('You guessed the number after ' + count + ' tries!');

1 Answer Unit 7,81 Answer Unit 7,81 Answer Unit 7,81 Answer Unit 7,81 Answer Unit 7,8

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