JavaScript 1
modulo
%. Returns the remainder from a division.
Fat Arrow
() =>
List the arithmetic operators:
+, -, *, /, %
When can a value be falsy:
0, Empty strings like "" or '', null (which represent when there is no value at all) undefined (which represent when a declared variable lacks a value), NaN (Not a Number)
String
Any grouping of characters on your keyboard (letters, numbers, spaces, symbols, etc.) surrounded by single quotes: ' ... ' or double quotes " ... ". Though we prefer single quotes. Some people like to think of string as a fancy word for text.
Number
Any number, including numbers with decimals: 4, 8, 1516, 23.42
.
The dot operator
data type
classifications we give to the different kinds of data that we use in programming
conditional statement
conditional statement checks specific condition(s) and performs a task based on the condition(s)
===
equal to
Console
an object, a collection of data and actions, that we can use in our code.
3 logical operators
and (&&) or (||) and not (bang !)
Parameter of a function
function ==>(this)<== { } . - To allow a function to accept data. provides the information the function needs to perform its job, e.g., how long should the phone vibrate, or how big a circle should be drawn
function declaration syntax
function idOfFunction ( ) { }
>
greater than
>=
greater than or equal to
Object
Collections of related data.
var
JS keyword for variable, creates/declares new variable
<
Less than
What are the seven fundamental data types in Javascript?
Number, String, Boolean, Null, Undefined, Symbol, Object
typeof
Returns the data type value
Undefined
This data type is denoted by the keyword undefined (without quotes). It also represents the absence of a value though it has a different use than null.
Boolean
This data type only has two possible values— either true or false (without quotes).
Null
This data type represents the intentional absence of a value, and is represented by the keyword null (without quotes).
Concatenation
This process of appending one string to another
A single line comment begins with:
Two forward slashes ( // )
Multi-line Comment
Will comment out multiple lines and is denoted with /* to begin the comment, and */ to end the comment. You can also use this syntax to comment something out in the middle of a line of code.
Write a template literal:
` ${} `
Operator
a character that performs a task in our code
Variable
a container for a value
How do we call, or use methods?
ie. 'example string'.methodName()
Write correct 'if' syntax:
if (true or false) { // block statement }
!==
is NOT equal to
<=
less than or equal to
How to start a JS doc:
main.js
/* */
multi-line comment
function
reusable block of code that groups together a sequence of statements to perform a specific task.
ternary operator
shorthand to simplify concise if...else statements.
List 2 types of code comments in JavaScript:
single line comment and multi-line comment
//
start of single line comment
multi-line comment (block comment)
starts with /* and ends with */, where all text between /* and */ is part of the comment
Symbol
unique identifiers, useful in more complex coding
What are the 3 variables?
var, let and const
single line comment
will comment out a single line and is denoted with two forward slashes // preceding it