Websites are comprised of multiple programming languages: HTML – Structure, CSS – Presentation & JS – Behavior

In order to write JavaScript programs you must know the basics of the JavaScript language. The rules and guidelines that makeup this language is called Syntax.
Syntax – the arrangement of words and phrases to create well-formed sentences in a language.

In this blog post for beginners we are going to cover some JavaScript terms and definitions as well as JavaScript data types.

Terms and Definitions you need to know

Statement – executable line of code

console.log( 'This is a statement' );

Expressions – produces or are values
Keywords – reserved JS words
Variables – generic containers for storing data. Should be full words, user camelCase.

JavaScript Data Types

  • Boolean – true or false values
  • String – literal characters
  • Number – numeric values & math operations
  • Null – empty value
  • Undefined – data type s set but has no value
  • Objects – data type that allows for a value to have properties
  • Symbols – unique identifiers

Settings up Variables in JS

To create a variable you need to declare the name then assign a value.
Below is an example of a boolean variable

var isUserLoggedIn = true;
if (isUserLoggedIn ) {
        console.log( 'User is logged in.' );

Below is an example of a string variable. Strings are characterized by data being wrapped in single quotations. You can concatenate strings using a plus sign.

var firstName = 'justin',
    lastName = 'estrada',
console.log( firstName );
fullName = firstName + ' ' + lastName;
console.log( fullName );

Below is an example of number variables.

var a = 5,
    b = 2,
c = a * b;
console.log( c );

There are different types of the data type Number as well.

  • Integers – whole numbers
  • Floating Points – decimal numbers
  • Positive & Negative Infinity

What is Nan? Unique data type signifying something is Not a Number. Usually returned due to an error.
A useful native JavaScript object is ‘Math’. Example:

// PI property
console.log( Math.PI );
// You can use powers and expressions
console.log( Math.pow( 13, 13 ) );

Brief overview of JavaScript Objects

Objecets are a data type that allows for a value to have properties.

var person = {
  id : 1,
  name : 'Justin'
// reassigning id = 3;  
console.log( );

What are JavaScript Symbols?

Symbols are a newer feature in JavaScript. Symbols are unique unchangeable values often used for naming custom properties.

var person = {
  id : 1,
  name : 'Justin'
IS_ONLINE = Symbol();
// reassigning id
person[IS_ONLINE] = true;
console.log( person[IS_ONLINE] );

Symbols are useful for having values that can’t be overwritten.