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);

Replace this text with the solution to the above question/problem.

Question 2

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

local variables are created in a function and cannot be referenced outside of the function whereas global variables are created outside of a function and can be called anywhere

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;
}

federal tax rate is global and every other one is local

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);

the code doesnt use the return command

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!");
}

no else statemtent

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);

Question 10

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

step over executes the current line and moves to the next line in the same function step into moves into the next 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.