JavaScript Statements

In HTML, JavaScript statements are "instructions" to be "executed" by the web browser.

JavaScript Statements

This statement tells the browser to write "Hello Dolly." inside an HTML element with id="demo":


document.getElementById("demo").innerHTML = "Hello Dolly.";
Try it Yourself »

JavaScript Programs

Most JavaScript programs contain many JavaScript statements.

The statements are executed, one by one, in the same order as they are written.

In this example x, y, and z are given values, and finally z is displayed:


var x = 5;
var y = 6;
var z = x + y;
document.getElementById("demo").innerHTML = z;
Try it yourself »

Semicolons ;

Semicolons separate JavaScript statements.

Add a semicolon at the end of each executable statement:

a = 5;
b = 6;
c = a + b;
Try it Yourself »

When separated by semicolons, multiple statements on one line are allowed:

a = 5; b = 6; c = a + b;
Try it Yourself »

JavaScript White Space

JavaScript ignores multiple spaces. You can add white space to your script to make it more readable.

The following lines are equivalent:

var person = "Hege";
var person="Hege";

A good practice is to put spaces around operators ( = + - * / ):

var x = y + z;

JavaScript Line Length and Line Breaks

For best readability, programmers often like to avoid code lines longer than 80 characters.

If a JavaScript statement does not fit on one line, the best place to break it, is after an operator:


document.getElementById("demo").innerHTML =
"Hello Dolly.";
Try it Yourself »

JavaScript Code Blocks

JavaScript statements can be grouped together in code blocks, inside curly brackets {...}.

The purpose of code blocks is to define statements to be executed together.

One place you will find statements grouped together in blocks, are in JavaScript functions:


function myFunction() {
    document.getElementById("demo").innerHTML = "Hello Dolly.";
    document.getElementById("myDIV").innerHTML = "How are you?";
Try it Yourself »

JavaScript Keywords

JavaScript statements often start with a keyword to identify the JavaScript action to be performed.

Here is a list of some of the keywords you will learn about in this tutorial:

Keyword Description