JavaScript Review

Question 1

There are two functions being called in the code sample below. Which one returns a value? How can you tell?

var grade = calculateLetterGrade(96);
submitFinalGrade(grade);

grade will return a value due to the = sign and it holding a vlaue.

Question 2

Explain the difference between a local variable and a global variable.

a global variable is defined outside of all functions and can be accressed rom anywhere in the program, a local variable is defined within a function or block and can only be accessed within that scope.

Question 3

Which variables in the code sample below are local, and which ones are global?

var stateTaxRate = 0.06;
var federalTaxRate = 0.11;

function calculateTaxes(wages){
	var totalStateTaxes = wages * stateTaxRate;
	var totalFederalTaxes = wages * federalTaxRate;
	var totalTaxes = totalStateTaxes + totalFederalTaxes;
	return totalTaxes;
}

Global variables are stateTaxRate, federalTaxRate. Local varaibles totalStateTaxes, totalFederalTaxes, and totalTaxes

Question 4

What is the problem with this code (hint: this program will crash, explain why):

function addTwoNumbers(num1, num2){
	var sum = num1 + num2;
	alert(sum);
}

alert("The sum is " + sum);
addTwoNumbers(3,7);

Sum is not defined therefor crashing the program

Question 5

True or false - All user input defaults to being a string, even if the user enters a number.

True

Question 6

What function would you use to convert a string to an integer number?

parseint

Question 7

What function would you use to convert a string to a number that has a decimal in it (a 'float')?

parseFloat()

Question 8

What is the problem with this code sample:

var firstName = prompt("Enter your first name");
if(firstName = "Bob"){
	alert("Hello Bob! That's a common first name!");
}

You need to put a == for the paramater of the if statement it currently has = you need ==

Question 9

What will the value of x be after the following code executes (in other words, what will appear in the log when the last line executes)?

var x = 7;
x--;
x += 3;
x++;
x *= 2;
console.log(x);

The sum of x will be 20

Question 10

Explain the difference between stepping over and stepping into a line of code when using the debugger.

Stepping into the the line of code will allow you to examine the code that you are trying to debugg. Stepping over will allow you skip over the function.

JavaScript Review

Coding Problems

Coding Problems - See the 'script' tag at the bottom of the page. You will have to write some JavaScript code in it.