Javascript

Front 1

Is JavaScript case sensitive?

Back 1

Yes

Front 2

What do statements end with in JavaScript?

Back 2

;

Front 3

How do you comment in JavaScript?

Back 3

// = single line
/* this is a multi-
line comment */

Front 4

How do you integrate JavaScript into a block of HTML?

Back 4

<script>

Front 5

Are there variable "types" in JavaScript?

Back 5

No. JS is a weakly typed language, so it's agnostic on type.

Front 6

What is the syntax of an if loop?

Back 6

if (condition) {
//code block evaluated if the condition is true
//code block is skipped if the condition is false
}

Front 7

What is the difference between parentheses, brackets and braces?

Back 7

parentheses ()
brackets []
braces {}

Front 8

Strict equality

Back 8

===

used to evaluate two variables. It evaluates them at the "type" level.

Front 9

Equality

Back 9

==

evaluates two variables (used in condition statements). Does not evaluate at the "type" level.

Front 10

Assigning or setting a value

Back 10

=

used to set values

Front 11

Not equal

Back 11

!=

Used in condition statements

Front 12

Not strictly equal

Back 12

!==

used in condition statements

Front 13

Order of operations for JS

Back 13

+ - * /

Front 14

Logical "and" gate

Back 14

&&

used in condition statements. allows one to evaluate multiple conditions in a single line.

Front 15

Logical "or" gate

Back 15

||

used in condition statements. allows one to evaluate multiple conditions in a single line.

Front 16

How can you increment a value "i" by 1?

Back 16

i++ since the code reads left to right, this statement does not initially increment i. It increments it after the statement has been evaluated.

++i This statement increments i the first time around.
i += 1 This statement increments i the first time around.

Front 17

How can you de-increment a value "i" by 1?

Back 17

i--
--i
i-=1

Same rules as incrementing.

Front 18

What is a ternary operator? Please display the syntax of such an operator.

Back 18

A ternary operator is a syntax expression for a basic conditional expression.

(condition) ? (what happens if the condition is true?) : (what happens if the condition is false);

Front 19

What is necessary for a loop to work properly?

Back 19

1. Index or counter (usually "i")
2. Something that checks the condition
3. Increment the index

Front 20

While loop syntax

Back 20

while (condition) {
//code to evaluate while the condition remains true
//code block incrementing the value
};

Front 21

Do While loop syntax

Back 21

do {
//code block with incrementing value
} while (condition);

Front 22

For loop syntax

Back 22

for ( index; condition checker; incrementor) {
//code block
};

Front 23

What is a code break? What is the syntax?

Back 23

A code break allows for one to "break" out of a loop. Upon evaluation, it will skip to the code immediately after the loop.

syntax:
break;

Front 24

What is a "continue" in a code block?

Back 24

If evaluated during a loop, "continue;" will break the sequence of the current iteration of a loop, and begin evaluating from the top of the loop again.

Front 25

What is a function in JavaScript?

Back 25

A block of code that will be executed when someone calls on it. It can accept parameters. Usually, these are defined at the top of a JS document.

Front 26

What is the syntax of a function in JavaScript?

Back 26

function functionName( parameters, are, separated, by, commas, no_parameters_required) {
//code
}

Front 27

Can a JS function return information?

Back 27

Yes, but it is not required to return anything.

Front 28

What happens if you provide a mismatched number of variables to a JS function?

Back 28

Missing variables will be left as undefined. if your code can run with undefined variables, it will work. If not, it will not work.

Extra variables will simply be ignored.

Front 29

What is a local variable?

Back 29

A variable that exists only within a function.

Front 30

What is a global variable?

Back 30

A variable that exists within the whole document of code.

Front 31

What is an array?

Back 31

It is an object.
It is used to store multiple values in a single variable.

Front 32

What indicates an array (3 ways)?

Back 32

1. []; square brackets
2. new Array();
3. Array();


var variableName = [bla, bla, bla, 3, bla, bla, "hi"];

Front 33

Can you have an empty array?

Back 33

yes, you can populate an array later. For example:

var VariableName = [];
VariableName[0]=50;
VariableName[1]="Taylor";

etc...

Front 34

What are some methods for the array object?

Back 34

variablename.join()
variablename.sort()
variablename.length()
variablename.reverse()

Front 35

how do you collect tag names from an HTML document and store them in a variable named "myArray"?

Back 35

var myArray = document.getElementsByTagName("a");

//this code will find all "a" tags from the document "document" and place them in an array

Front 36

NaN

Back 36

Not a Number (output when a math expression didn't make sense)

Front 37

function isNaN(variable);

Back 37

returns true if the "variable" is not a number
returns false if the "variable" is a number

Front 38

function !isNaN(variable);

Back 38

returns true if the "variable" is a number
returns false if the "variable" is not a number

//easier to comprehend with the double negative
//ask yourself, is "variable" a number?

Front 39

what is "Math" in JavaScript? (object or method)

Back 39

Object

Front 40

what is the escape sequence for a quote?

Back 40

" bla bla bla \"this is something i put in quotations\" bla bla bla."

Front 41

What is a string in javascript? (method or object)

Back 41

Object

Front 42

What does the ".split" method do to a string?

Back 42

Splits the words of a string. makes an array of the words...

Front 43

what is "Date" in javascript? (method or object?)

Back 43

Object

Front 44

What will console.log(Date()) output in mozilla?

Back 44

The current timestamp to the millisecond

Front 45

Var today = new Date();

today.getMonth();

//what will this return?

Back 45

returns month (0-11)

Front 46

Var today = new Date();

today.getFullYear();

//what will this return?

Back 46

returns YYYY (not zero based)

Front 47

Var today = new Date();

today.getDate();

//what will this return?

Back 47

returns the day of the month

Front 48

Var today = new Date();

today.getDay();

//what will this return?

Back 48

returns 0-6 (day of the week)

Front 49

Var today = new Date();

today.getHours();

//what will this return?

Back 49

returns hours (24)

Front 50

What is a document in JS?

Back 50

(Object) It is the root node of an HTML document and the "owner" of all other nodes.

Front 51

What is an object in JS?

Back 51

A special kind of data with properties and methods

Front 52

What is a method in JS?

Back 52

Actions that can be performed on objects

objectName.methodName()

.join
.slice
.indexOf
.push
.splice
etc...

Front 53

What is a property in JS?

Back 53

Values associated with an object

objectName.propertyName

.value
.length
.name
.constrictor
etc...

Front 54

What are the four steps towards creating a DOM element (using the example of a new text node)

Back 54

1. Create variables for the new elements
var newHeading = document.createElement("H1");

2. Create new variables (nodes) for the text of the new element
var newText = document.createTextNode("Did you know?");

3. Append the text nodes with the new elements
newHeading.appendChild(newText);

4. Append the new element with the document
document.getElementById("trivia").appendChild(newHeading);
//appends the new element to a specified spot in the document ("trivia")