Modular, loops, strings.

Question 1

difference between parameter and argument.

Answer 1

• argument is more specific than the parameter

- parameters can have multiple arguments

Question 2

function addTwoNumbers(a, b) {

	var result = a + b;
	alert(result);
}

addTwoNumbers(5, 10);

*what is the parameter?

Answer 2

the inputs of a, b

Question 3

function addTwoNumbers(a, b) {

	var result = a + b;
	alert(result);
}

addTwoNumbers(5, 10);

*what is the argument?

Answer 3

the inputs of 5, 10

Question 4

variable scope

Answer 4

• variables created within a function
• these variables are limited to the function

Suppose you create a function:

function myFunction() {
   var x = 500

}

Now, if you simply wrote code to alert (x), nothing will happen because X was created within the function and limited to the function.

Question 5

global variable

Answer 5

• variable created outside of a function.

- can be used anywhere in your code

Question 6

scripts tag

Answer 6

• used to link other javascript pages together

- think external stylesheet for javascript

Question 7

javascript script tag

what does it look like?

Question 8

iteration

Answer 8

the process of looping code

sometimes iteration IS called loop or looping

Question 9

to use the javascript looping or iteration ability, we replace…

Answer 9

if with while

example:

var a = 1;

while (a >10) {

alert (a)
}

Question 10

infinite loop

Answer 10

• the result of not incrementing or modifying an index

Question 11

steps to creating a loop using WHILE

Answer 11

1) set up the index
2) check the condition
3) increment the index

Question 12

for loop

Answer 12

simplifies the while loop

Question 13

use the for loop:

var i = 1
while (i

Answer 13

for (var i=1; i

Question 14

do while loop

Answer 14

executes the loop before checking the condition

Question 15

change to do while loop

var i = 1
while (i

Answer 15

var i = 1;

do {i++
} while ( i

Question 16

NaN

Answer 16

Not a number

what displays when javascript does not understand.

Question 17

var foo = 5;
var bar = 5;

alert ( foo + bar);

*what will display? why?

Answer 17

10

the values for foo and bar are numbers and the + represents adding

Question 18

var foo = "5";
var bar = "5";

alert ( foo + bar);

*what will display? why?

Answer 18

55

the two “5” represents character strings so “5” + “5” will CONCATONATE

Question 19

var foo = 5;
var bar = "5";

alert ( foo + bar);

*what will display? why?

Answer 19

55

if one is a string then that one “takes charge”

Question 20

var foo = 5;
var bar = "5";

alert ( foo * bar);

*what will display? why?

Answer 20

NaN

javascript will not understand a number multiple by a character string

Question 21

how would you convert the var a = “55” into a variable a being 55

Answer 21

using the Number function

var a = "55"
var newVariable = Number(a)

now newVariable is a variable that is = 55

Question 22

what javascript function would you use to check if a viable is not a number?

Answer 22

isNaN

^ is NOT a number

Question 23

what javascript function would you use to check if a viable is a number?

Answer 23

!isNan

^ is NOT NOT a number

Question 24

suppose you have a variable:

var a = “This is a”;

*How do you determine the # of character strings inside variable a

Answer 24

a.length

using the length property

Question 25

methods

Answer 25

functions but for character strings

Question 26

suppose you have a variable:

var a = “This is a”;

*How do you uppercase everything in a?

Answer 26

a.toUpperCase()

Question 27

suppose you have a variable:

var a = “This is a”;

*How do you convert all of a to lowercase?

Answer 27

a.toLowerCase()

Question 28

var a = "Hello";
var b = "hello";

are a and b the same?

Answer 28

NO

Question 29

Suppose you have:

var a = "Hello";
var b = "hello";

*how do you make a = b?

Answer 29

a.toLowerCase() == b.toLowerCase()

• this will change both a and b to “hello”
• or you can upper case in which case both a and bc will be “HELLO”

Question 30

suppose you have

var a = “We want something new”;

*how do you find the position of the world “something”?

Answer 30

var position = a.indexOf(“something”);

• now position will be = 9
• remember, the first letter/number is 0 while using indexing
• in var a = “We want something new”; - W = 0, e =1, (white space) = 3, etc…

Question 31

if you use indexOf method and receive a -1, that means….

Answer 31

the string does not exist you are trying to index.

Question 32

what methods exist to break character strings up? (3)

Answer 32

1) .slice
2) .substring
3) .substr

Question 33

suppose you have:

var a = “Yet another variable”;

use slice to pull out “other” from a

Answer 33

var b = a.slice (6, 11)

Question 34

var a = "aaaaaa";
var b = "bbbbbb";

what is large, a or b?

Answer 34

a

because javascript looks at the first character and seems a is larger than b, it goes alphabetically

Question 35

var a = "aaaaaa";
var b = "Bbbbbb";

what is large, a or b?

Answer 35

B

javascript assumes letters that are capitalized are larger values.

Question 36

regular expressions

Answer 36

• finds patters and expressions within character strings
• used if you want to know is a string is a URL, if a string matches the basic requirements of an email address, or if a string has numbers, etc…

Question 37

regular expressions (2)

Answer 37

1) create expression

2) apply and ask if it matches