JavaScript Review

Question 1

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

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

the function that returns the falue is calculateLetterGrade

Question 2

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

a global function is declared outside of the function wheras a local is inside of the function (){}

Question 3

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

const stateTaxRate = 0.06;
const federalTaxRate = 0.11;

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

the locla is the calculateTaxes function and the global is the totalTaxes

Question 4

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

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

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

since its a local function it cannot be declared outside the function using const, so thats why it is crashing.

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:

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

single = sign

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)?

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

answer should be 20

Question 10

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

one skips the details while the other goes into the details

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.