JavaScript Statements

❮ Previous Next ❯

JavaScript Programs

A computer program is like a set of directions for a computer to follow.

In a computer language, these commands for programming are known as statements.

A JavaScript program is a set of commands written using JavaScript.

In HTML, the web browser runs JavaScript programs.

JavaScript Statements

JavaScript code consists of:

Words, Symbols, Phrases, Specific Words, and Notes.

This instruction tells the web browser to display the words "Hello Dolly." within a specific part of a webpage identified by the unique name "demo."

Many JavaScript programs have lots of JavaScript statements.

The instructions are carried out step by step, exactly in the same order they are written.

JavaScript programs and statements are commonly referred to as JavaScript code.

Semicolons ;

In Javascript, semicolons are used to split different instructions or commands.

Put a semicolon at the end of every command that can be executed:

You can put several commands on one line if you separate them with semicolons.:

Online, you may come across instances where semicolons are missing. Using semicolons at the end of statements is not obligatory, but it's strongly advised.

JavaScript White Space

JavaScript doesn't pay attention to extra spaces. You can include extra spaces in your code to make it easier to read.

Here are some lines that mean the same thing.

let person = "Hege";
let person="Hege";

A helpful tip is to add spaces before and after operators like =, +, -, *, and / in your code.

let x = y + z;

JavaScript Line Length and Line Breaks

To make code easier to read, programmers usually prefer to keep each line of code shorter than 80 characters.

If a JavaScript instruction is too long to fit on one line, it's a good idea to split it after an operator:

JavaScript Code Blocks

You can put JavaScript statements together in code blocks by using curly braces {...}.

You can often see statements grouped together in blocks within JavaScript functions.

In this guide, we use two spaces to organize our code neatly. Later on, you'll get to know more about functions through this tutorial.

JavaScript Keywords

JavaScript commands usually begin with a special word to tell the computer what to do in JavaScript.

Our Reference for Special JavaScript Words contains a complete list of all the important words in JavaScript.

Here's a list of words you'll discover in this tutorial:

Keyword	Description
var	"Defines a variable."
let	States the existence of a block variable.
const	States that something remains unchanged as a block.
if	Indicates a group of instructions to be carried out when a certain condition is met.
switch	This code is like a signpost for a group of instructions to run under different conditions.
for	Defines a group of commands to repeat in a loop.
function	Defines a function.
return	Leaves a function.
try	Adds a way to deal with mistakes in a group of instructions.

JavaScript keywords are special words that have a specific meaning in the language. You can't use these words as names for your variables.

<!DOCTYPE html>
<html>
  <body>
    <h2>JavaScript Statements</h2>
    <p>A <b>JavaScript program</b> is a list of <b>statements</b> to be executed by a computer. </p>
    <p id="demo"></p>
    <script>
      let x, y, z; // Statement 1
      x = 5; // Statement 2
      y = 6; // Statement 3
      z = x + y; // Statement 4
      document.getElementById("demo").innerHTML = "The value of z is " + z + ".";
    </script>
  </body>
</html>

<!DOCTYPE html>
<html>
  <body>
    <h2>JavaScript Statements</h2>
    <p>In HTML, JavaScript statements are executed by the browser.</p>
    <p id="demo"></p>
    <script>
      document.getElementById("demo").innerHTML = "Hello Dolly.";
    </script>
  </body>
</html>

<!DOCTYPE html>
<html>
  <body>
    <h2>JavaScript Statements</h2>
    <p>JavaScript statements are separated by semicolons.</p>
    <p id="demo1"></p>
    <script>
      let a, b, c;
      a = 5;
      b = 6;
      c = a + b;
      document.getElementById("demo1").innerHTML = c;
    </script>
  </body>
</html>

<!DOCTYPE html>
<html>
  <body>
    <h2>JavaScript Statements</h2>
    <p>Multiple statements on one line are allowed.</p>
    <p id="demo1"></p>
    <script>
      let a, b, c;
      a = 5; b = 6;  c = a + b;
      document.getElementById("demo1").innerHTML = c;
    </script>
  </body>
</html>

<!DOCTYPE html>
<html>
  <body>
    <h2>JavaScript Statements</h2>
    <p> The best place to break a code line is after an operator or a comma. </p>
    <p id="demo"></p>
    <script>
      document.getElementById("demo").innerHTML = "Hello Dolly!";
    </script>
  </body>
</html>

<!DOCTYPE html>
<html>
  <body>
    <h2>JavaScript Statements</h2>
    <p>JavaScript code blocks are written between { and }</p>
    <button type="button" onclick="myFunction()">Click Me!</button>
    <p id="demo1"></p>
    <p id="demo2"></p>
    <script>
      function myFunction() {
        document.getElementById("demo1").innerHTML = "Hello Dolly!";
        document.getElementById("demo2").innerHTML = "How are you?";
      }
    </script>
  </body>
</html>

❮ Previous Next ❯

JavaScript Tutorial

JS Math

JS Versions

JS Objects

JS Functions

JS Classes

JS Async

JS HTML DOM

JS Browser BOM

JS Web APIs

JS AJAX

JS JSON

JS vs jQuery

JS Graphics

JavaScript Statements

JavaScript Programs

JavaScript Statements

Semicolons ;

JavaScript White Space

JavaScript Line Length and Line Breaks

JavaScript Code Blocks

JavaScript Keywords

Web Development