People often think that Java and JavaScript are somehow related. While it is easier to code in JavaScript if you already know Java, the languages have little in common.

In the 1990s, Netscape developed a scripting language called LiveScript.

To gain acceptance, the company saw an opportunity to play off of the growing success of Java, so the name was changed to JavaScript.

What Is JavaScript?

JavaScript is a scripting language that develops client-side code that runs in web browsers.

Because JavaScript is a text-based language, it does not require compiling. Instead, it uses an interpreter to translate source code into executable code.

Designed as a web development language, the functions can run after a page is loaded, making it ideal for validation and interactivity on websites or mobile apps.

Code in JavaScript can be inserted into a web page’s HTML, allowing for smoother integration of JavaScript functions on a page.

Over the years, JavaScript has become more robust and is often used for server-side applications.

Today, there are extensive libraries that give developers faster access to more dynamic capabilities.

Basic Coding Terminology

Before discussing JavaScript in more detail, let’s define a few terms.

  • Floating-point numbers are values with no set precision; i.e., no restrictions on the number of integers before or after the decimal point.
  • Primitive, when applied to data types, refers to those elements that are built into the computer language.
  • Algorithms are a set of instructions for the computer to process.
  • Syntax is a set of rules that define how a language is structured. It includes such things as the use of punctuation or symbols.
  • Semantics is the meaning of a language’s expressions or statements.

We define the coding terms, such as data types, operators, or data structures, elsewhere in the article.

Data Types

Data types stipulate the type of data that a function uses. The five most common data types are integer, floating-point, character, string, and Boolean.

JavaScript allows the following primitive data types:

  • Numbers. Numbers include integers and decimal values. Floating-point data types are part of numbers.
  • Strings. Strings refer to a series of words defined as a single set of data. Include characters in strings.
  • Boolean. Boolean data types are logical true/false constructions.
  • Null. The value of this data type is always null or nothing.
  • Undefined. Variables that do not have an assigned value are undefined data types.

Three additional data types are allowed; however, they are designed for more complex applications.

  • Object. JavaScript objects are a composite data type that allows for more complex data structures.
  • BigInt. This data type allows integer values that exceed the established safe limit.
  • Symbol. Appearing in 2015, this data type is used in conjunction with objects to allow for complex data structures.

Using the above three data types requires a thorough understanding of JavaScript and may not be covered in beginning JavaScript classes.

Data Structures

Data structures are ways to store and organize data for easier manipulation. They determine data collection.

They establish how data can be accessed and how data is related. Properly designed and implemented data structures mean that programs run faster and more efficiently.

The following are examples of JavaScript data structures.

  • Arrays. JavaScript arrays store data in memory. At the time of creation, there is a fixed length with data accessed through a numeric index.
  • Queues. Queues are sequential data structures that operate on a first in, first-out or FIFO process. This operation is in contrast to the first in, last out, or FILO processing.
  • Linked Lists. Data exists outside physical memory. Instead, nodes store data that contains pointers to other nodes. Thus, making it easier to add and delete elements without data reorganization.

Other types of data structures include

  • Trees. Trees are relational data structures creating hierarchical structures. They use nodes that contain elements and pointers; however, all nodes must branch off of a root node.
  • Graphs. Another relational-based structure that works in situations where data has multiple connections to other data.
  • Hash Tables. Hash tables store large amounts of data by establishing a key for fast retrieval of a paired value.  It is a complex data structure.


Operators describe what operations can be performed on data.

For example, in the equation 2+2=4, the “+” is the operator because it defines what operation to perform on the numeric values.

JavaScript supports the following types of operators.

  • Arithmetic Operators
  • Comparison Operators
  • Logical (or Relational) Operators
  • Assignment Operators
  • Conditional (or ternary) Operators

Additional operators include Bitwise, String, and Comma. Operators in JavaScript provide programmers with an extensive set of options for data manipulation

How to Add JavaScript to HTML


There are two ways to use JavaScript with HTML. One way is to enter the JavaScript code directly into the HTML.

JavaScript code appears in the head of the HTML between script tags. For example, How to write JavaScript  

The other, and more preferred method, is to save the code in files and call the files from the HTML page. This method allows multi-page access for the same JavaScript code.

The name of the file appears between the script tags. Further, the file must be accessible to the HTML web page.

How to Write JavaScript

Learning JavaScript is like learning most programming languages. Once you understand the syntax, it’s a matter of learning the semantics of the language such as data types.

Then, it is practice, practice, practice.

As with any language — human or computer — the more you use it, the better you become.

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