Javascript Basic Grammar"

I want to put these basic grammar all together here. To make things more convenient.

JS Basics

Computer programs are lists of instructions. They are run linearly.

Code is what computer programs are written in.

Grammar is the foundation of language. Programming languages are built upon sets of tules called syntax.

Semicolons is optional to be used, but is neccessary when having two statements on the same line.

Syntaxt

Includes keywords like var, return and true.

Comments are denoted by //. They are not read by the computer.

Variables

Store data and are the building blocks of Javascript.

Each variable is defined by a case-sensitive name.

var myVariable = "data"
console.log(myVariable)

String

String can be sequences of characters. It can also include spaces, punctuation, and numbers.

They are identified by double quotes.

Numbers

There is no need to use quote when you value numbers.

var myNumber = 10

Expressions

An expression can combine numbers, string and variables to output a value. They are evaluated from left to right when coding.

Arithmetic

The four basic forms of arithmetic are represented by symbols called operators and are used when creating expressions.

var myNumber = 10 + 2
console.log(myNumber)

The same as C grammar, they are +, -, *, / and %。

Booleans

Booleans can be used to store true or false outcomes.

var myBooleans = true
console.log(myBooleans)

Comparisons

There are six kinds of way to compare data.

> Greater than
< Less than
>= Greater than or equal to
<= Less than or equal to
!= Not equal to 
== Equal to

Booleans work closely with comparision operators and rely on them to determine whether the boolean will output a true or false value.

Variables

Variables are containers for storing values and are essential to write complex computer programs.

Delaration

You can use var to declare a variable.

Naming

A variable's name is unique and case-sensitive.
You can put your variable's name after the keyword var.

Assignment

To assign a value, you can use =.

var myName = "Ben"
console.log(myName)

Reassignment

Variables are containers for values and you can replace the existing value in a variable with a new value.

Types

Data types: number, string, boolean.
Variables can store values of any data type.

var myString = "String"
var myNumber = 33
var myBoolean = true

Undefined

The data type undefined denotes the absence of a value.
If you declare a variable, but don't assign a value, it automatically holds the value undefined.

var myNothing
console.log(myNothing)

Then the computher will output "undefined".

Initialization

When a variable is given a value it is called initialization.

Type Comparisons

You can use === and !== to compare the value and data type.

var Something = 10 === "10"
console.log(Something)

Then the computer will output false.

Functions

Functions are the verbs of programming.
They tell the computer to do a set of actions.

function myFunction(){
console.log("Function!")
}

myFunction()

Console.log

This funcion has the computer print data to the console for your viewing.

Declaring Functions

You can use the keyword function to declare a funcion and give is an action to execute inside {}.

Storing Functions

You can also use a variable to store function.
This can make it more easier when we use a funcion.

var myFunction = function(){
console.log("Funciont!")
}

myFunction()

Parameters

Parameters are variables you give a function as inputs inside ().
Parameters are given specific values when you call the function.

var getCost = function(price){
console.log( "$" + price )
}

getCost(20)

Then the price is a parameter.

Calling Functions

When you call a function you are assigning a value to your parameters.
This value is called an argument.

Arguments

Arguments are the values you assign to parameters.

20 is an argument.

Missing Arguments

If a function with a parameter is called with a missing argument, that parameter is assigned the value undefined by default.

function say(myname){
  console.log(myname)
}

say()

Body

Anything inside () is considered the body of the function, and is executed when the function is called.

function getcost(price){
  var tip = price * 0.2
  var cost = price + tip
console.log("$" + cost)
}

getcost(20)