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68 Cards in this Set
- Front
- Back
switch is a legal identifier in JavaScript.
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False
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count++; is equivalent to count = count + 1;
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True
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Every function must have a return statement.
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False
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In JavaScript, the function keyword is used to define a function.
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True
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When a function is called, its local variables initially contain the value 0.
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False
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Actual and formal function parameters must have the same name.
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False
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A function always returns the value 0.
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False
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When a function is called, the number of arguments passed should match the number of formal parameters.
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True
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After a function has returned, the values stored in its local variables are copied into variables in the calling function that have the same name.
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False
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The values stored in the local variables of a function are not saved when the function exits.
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True
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Formal parameters must also be declared inside of a function using the var keyword.
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False
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JavaScript is an interpreted language.
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True
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If the variables a and b are holding the values 0 and 1, respectively, what is the value of the following expression : ( a || b ) ?
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True
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If the variables a and b are holding the values 0 and 1, respectively, what is the value of the following expression : ( a && b ) ?
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False
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If the variables a and b are holding the values 1 and 2, respectively, what is the value of the following expression : ( a + b ) ?
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True
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If the variables a and b are holding the values 0 and 6, respectively, after the statement a += b the new values of a and b are both 6.
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False
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All array elements are initialized to 0 when the array is created.
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False
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The default case is required in the switch selection structure.
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False
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The default case must be the last case in the switch selection structure.
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False
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The break statement is required in the default case of the switch selection structure.
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False
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An array is used store a list of items.
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True
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Array subscripts must always start at 0.
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True
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The function keyword is used when making a function call.
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False
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The fourth element of an array named bob is bob[4]
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False
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Arrays must always be initialized using a for loop.
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False
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Given the function call,
PrintGreeting(); how many arguments does the function have? |
0
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The function header comment
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[b.] gives information about the function to the person reading the code.
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What is the output of the following code fragment?
var a = 3, b = 17 ; a = b % a ; b++ ; alert("a = " + a + ", b = " + b); |
[d.] a = 2, b = 18
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The output of the following program fragment is:
test = 1 ; if (test = 2) { alert("Beam down the landing party.\n") ; } else if (test == 1) { alert("Jim, he's dead.\n") ; } else if (test == 0) { alert("Scotty, four to beam up.\n") ; |
[a.] Beam down the landing party.
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Which of the following statements will print out the variable x with exactly 1 decimal place, e.g. 123.4
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[a.] alert (x.toFixed(1));
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A single JavaScript statement that decrements the value of x, giving x a new value is
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[a.] x--;
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How many arguments does the following function call have?
ave = FindAverage(num1, num1); |
2
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How many arguments does the following function call have?
PrintMessage("Hello there!"); |
1
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Which of the following is a function header for a function that has only 1 parameter?
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[b.] function AddOne(num1)
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What is the index of the last element in an array of size 10?
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[c.] 9
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The character used to display a newline in an alert statement is
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[a.] \n
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The tag used to display a newline in a document.write() statement is
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[d.] <br />
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Which operator can be used on strings and numbers?
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[b.] +
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How can you increment the variable num by 1?
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[a.] num++
[b.] num = num + 1 [c.] num += 1 |
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When a variable is declared, what is its initial value?
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NULL (aka empty)
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Explain why it is sometimes necessary to use parseInt() or parseFloat() after a call to prompt().
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Because the prompt command doesn't know if it is capturing a string or a number
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Briefly describe one reason to write your own functions.
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It keeps you from having to write the same code over and over again
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Write a function called SumTwo that returns the sum of two numbers, where the numbers, num1 and num2 are passed to it.
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function SumTwo(num1, num2) {
return parseInt(num1) + parseInt(num2); } |
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Name two benefits of using constants in a program.
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You can't accidentally change the value of a constant. Constants make a program easier to modify
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Write a function called Smallest that takes three arguments, x, y and z and returns the smallest of the three arguments. You can assume x, y and z are numbers.
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function Smallest(x,y,z) {
var smallest = z; if (y < smallest) { smallest = y; } if (x < smallest) { smallest = x; } return smallest; |
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What is the starting index of an array?
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0
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Briefly describe why the function definitions are placed in the <head> section of the document.
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It is easier to organize and understand the program
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Write a function called AlertEven that takes 1 argument, n, and alerts whether the value is even or not. The function should not return anything. For example if n is 6, the output would be "6 is even". If n is 7, the output would be "7 is not even".
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function AlertEven(n) {
if (n % 2 == 0) { alert("even"); } else { alert("odd"); } } |
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In an array declared with n elements, what is the index of the last element ?
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n-1 because the first element of the array is index 0 (e.g. myarray[0] )
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Write the statements that would declare a 10-element array and initialize all of its elements to 1.
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var myarray = new Array(10);
myarray=1; |
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Write a function called Average that takes three number parameters n1, n2, and n3 and returns the value of the average of the three.
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function Average(n1, n2, n3) {
return ((n1 + n2 + n3) / 3); } |
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Write a function called SumN that takes one parameter, n, and returns the sum of the integers from 1 to n.
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function SumN(n) {
var sum = 0; var i; for (i=1;i<=n;i++) { sum = sum + i; } return sum; } |
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Write a function called FeetToInches that takes numFeet as an argument and returns the number of inches in that many feet.
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function FeetToInches(numFeet) {
return (numFeet * 12); } |
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Write a function called PrintBox that will print a rectangle made up of any character passed to it. Here is the function header:
function PrintBox (rows, columns, ch) This call to PrintBox, PrintBox(3, 10, "$"); should print: $$$$$$$$$$ $$$$$$$$$$ $$$$$$$$$$ |
function PrintBox(rows, columns, ch) {
var i; var j; for(i=1;i<=rows;i++) { for(j=1;j<=rows;j++) { document.write(ch); } } } |
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Write a set of one or more statements that will print out one of the brief messages given in the table below, depending on a person's grade point average. Assume that the grade point average has already been read into a variable called gpa. Include code to print a warning message if the value of gpa is not in the range 0.0 to 4.0. You should decide which control structure (if, if-else, switch, etc...) is appropriate.
GPA range Student Rating 3.50 - 4.0 Dean's list 2.0 - 3.49 Satisfactory 1.0 - 1.99 Probation 0.0 - 0.99 Suspended |
if (gpa < 0 || gpa > 4) {
alert("gpa is not correct"); } else { document.write("<b>GPA range Student Rating"); if (gpa >= 3.50) { document.write("3.50-4.0 Dean's List"); } else if (gpa >= 2.0) { document.write("2.0-3.49 Satisfactory"); } else if (gpa >= 1.0) { document.write("1.0 - 1.99 Probation"); } else { document.write("0.0 - 0.99 Suspended"); } } |
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Given an array of size 100 called numbers, write a code segment that would find the average of the array elements. You can assume that the array has already been initialized to hold values.
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var sum = 0;
var i; for (i=1;i<=99;i++){ sum=sum+numbers(i); } alert("Average is " + (sum / 100)); |
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Given an array of size 100 called numbers, write a code segment that would find the smallest element in the array. You can assume that the array has already been initialized to hold values.
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var smallest=numbers(0);
var i; for(i=1;i<=99;i++){ if (numbers(i) < smallest) { smallest = numbers(i); } } alert("Smallest is " + smallest); |
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Given an array of size 100 called numbers, write a code segment that would find the largest element in the array. You can assume that the array has already been initialized to hold values.
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var largest=numbers(0);
var i; for(i=1;i<=99;i++){ if (numbers(i) > largest) { largest = numbers(i); } } alert("Largest is " + largest); |
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What is wrong with the following code segment? Modify the code so it works correctly.
var i = 1; //this while loop displays the numbers 1-10 while (i <= 10) { alert("i is " + i); i--; } |
var largest=numbers(0);
var i; for(i=1;i<=99;i++){ if (numbers(i) > largest) { largest = numbers(i); } } alert("Largest is " + largest); |
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Give a description of a problem/program where you would use an array and explain why you would choose to use an array. What would the alternative to an array be?
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Change the "i--" to "i++"
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alert ("JavaScript\nis\nfun.");
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Output:
JavaScript is fun. |
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var a = 2, b = 3;
b = b * a; b++; a += b; alert (a + " " + b); |
Output:
"9 7" |
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var a = 5, b = 4;
b += a; b++; a = a - b; document.write (a + " " + b); |
Output:
"5 10" |
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var n = 1234;
while (n > 0) { document.write(n + "<br />"); n = n / 10; n = Math.floor(n); } /* Hint: The Math.floor() function truncates a number downwards to the nearest integer. For example, the floor of 34.5 would be 34 */ |
Output:
1234 123 12 1 |
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var m;
for (m = 1; m <= 5; m++) { switch (m) { case 1: document.write ("one"); break; case 2: document.write ("two"); break; case 3: document.write ("three"); break; default: document.write ("Default case"); } document.write ("<br />"); } |
Output:
one two three Default case Default case |
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var x;
for (x = 4; x >= 0; x--) { switch (x) { case 3: document.write ("tres"); break; case 2: document.write ("dos"); break; case 1: document.write ("uno"); break; default: document.write ("Default case"); } document.write ("<br />"); } |
Output:
Default case tres dos uno Default case |
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<head>
<script type="text/javascript"> <!-- function X (m) { document.write("In function X: " + m + "<br />"); return (m + 2); } //--> </script> </head> <body> <script type="text/javascript"> <!-- var m; m = X(5); document.write("After the call to function X: " + m); //--> </script> |
Output:
In function X:5 After the call to function X: 7 |
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<head>
<script type="text/javascript"> <!-- function Foo (num) { num++; document.write("In function Foo: " + num + "<br />"); return num; } //--> </script> </head> <body> <script type="text/javascript"> <!-- var num = 7; Foo(num); document.write("After the call to function Foo: " + num); //--> </script> |
Output:
In function Foo:8 After the call to function Foo:8 |