Part 4- A Smarter Way to Learn JavaScript

Question 1

In this piece of code, what does: var i = 0 mean?

for (var i = 0; i<=4; i++) {
//code to run goes here
}

Answer 1

It’s the “counter”. It changes in each iteration so that eventually the FOR loop will end.

Question 2

In this piece of code, what does i<=4 mean?

for (var 1 = 0; i<=4; i++) {
//code to run goes here
}

Answer 2

*it’s the “loop limiter”

*it tells you how many iterations will run.

Question 3

In this piece of code, what does i++ mean?

for (var 1 = 0; i<=4; i++) {
//code to run goes here
}

Answer 3

*it’s the “incrementor” (my name)

*it adjusts the variable i for the next iteration

Question 4

What’s the format of the first line of a FOR loop?

Answer 4

for (var i = 0; i<=4; i++) {

Question 5

How would you code to loop through a test repeatedly?

Answer 5

FOR loop with an embedded IF loop:

for (var 1 = 0; i<=4; i++) {
if (x === y) {
//do this code
}
}

Question 6

What’s the point of a FOR loop? What does it do?

Answer 6

It repeats the same code over and over, each time with a different value.

This is looping, AKA iteration.

Question 7

What if you want to FOR loop your way through each value in an array, but you don’t know how long the array is?

Answer 7

*set the second part of a FOR loop to this: i < arrayName.length.

*Or you can set up a variable equal to the length of the array:
var numElements = arryName.length, then you put it in the “i <” spot (second part of a FOR loop):
for (var i = 0; i < numElements; i++)

Question 8

How do you set up a variable equal to the length of an array?

Answer 8

var x = arrayName.length;

Question 9

Do Boolean use quotation marks like a string?

Answer 9

No. It’s just true and false

Question 10

What is a flag and how do you use it in looping?

Answer 10

*a flag is a variable that starts as one value, then changes value if something happens.

*in a FOR loop, you might set a flag to a Boolean value so that when the loop matches something, it returns the other Boolean value

Question 11

What’s a BREAK

Answer 11

break;

A keyword that ends your loop. Put it in your code so if you get the right answer, it doesn’t keep looping and looping.

Question 12

What is an assignment operator?

Answer 12

= += -=
*= /= %= :

*An assignment operator is the code used to assign a new value to a variable, property, event, etc.

Question 13

Can you nest FOR loops?

Answer 13

Yes. You can use a j for the first nested loop, k for the next, etc etc.

Think of the nested loop as the second hand and the original loop as the minute hand. The nested loop will go through all of its iterations, then the original loop will increment its variable. Then the nested loop will go through all its iterations again, etc etc

Question 14

What are the two types of control flow statements in JavaScript?

Answer 14

*Conditional

*Iterative (Looping)

Question 15

Change letters to lowercase?

Answer 15

var str1 = str1.toLowerCase();

Question 16

Can slice() be used on a string?

Answer 16

Yes. You can use it directly on the string, or on a variable that represents the string.

Question 17

What does this do?
text.indexOf(“Apple”);

Answer 17

*it looks through the variables text
*it finds the index number of the first character of the string apple

Question 18

What is text.indexOf( ); used for?

Answer 18

Finding a phrase in a body of text. It only finds the first character of the phrase, but that’s all the info you need to create code to modify the phrase.

Question 19

What is one drawback of text.indexOf()?

Answer 19

It only finds the FIRST instance and not other instances. To find other instances, you would have to loop.

Question 20

How do you find the last place a phrase appears in a text?

Answer 20

text.lastIndexOf(“phrase you’re looking for”):