Welcome to compeducational.com: JavaScript: Statements

Statements in Javascript are the step by step instructions to be executed by the computer. A JavaScript program is built up of its programming statements.

Javascript statements may composed of :

Variable

Value

Operators

Expressions

Keywords and

Comments

The statements are inserted in HTML document between <script> and </script> tags and run by web browsers.

see an easy example:

<html>

<body>

<h2>JavaScript Statements</h2>

<p>JavaScript Statements are the step by step instructions to be executed by computer. </p>

document.getElementById("demo").innerHTML = "Hello World.";

</script>

</body>

</html>

Now try the above program yoursef in 'try it editor' given here.

Try it yourself editor


Code <html> <body> <h2>JavaScript Statements</h2> <p>In HTML, JavaScript statements are executed by the browser.</p> <p id="demo5"></p> <script> document.getElementById("demo5").innerHTML = "Hello World."; </script> </body> </html>	Output

A JavaScript program may consists of many statements and these statements are executed one by one in the order, in which they are written. Each statement separates from each other by ;(semicolon).

For ex:

<html>

<body>

<h2>JavaScript Statements</h2>

<p>JavaScript statements are instructions executed one by one.</p>

var a, b, c; //declair three variables named a, b and c

a = 5; //assign the value 5 to a

b = 6; //assign the value 6 to b

c = a + b; //assign the value of a+b to c

document.getElementById("demo").innerHTML = c;

</script>

</body>

</html>

Now try it yourself in below editor

Try it yourself editor


Code <html> <body> <h2>JavaScript Statements</h2> <p>JavaScript statements are instructions executed one by one.</p> <p id="demo7"></p> <script> var a, b, c a = 5; b = 6; var c = a + b; document.getElementById("demo7").innerHTML = c; </script> </body> </html>	Output

In above editor change any value of variable a or b, and see the result. We can use 'Let' keyword to store a direct value into a variable(like c = 7 + 6). But when we store a variable into another variable (like c =a + b) then we use 'var' keyword.

We can also write multiple statements in one line separated from each other by semicolon.

like var a, b, c; a = 5; b = 6;

c = a + b;

You can try in above editor window.

JavaScript ignores the multiple spaces inside statement. For example c=a+b and c = a + b, both are equivalent.

For best readability in JavaScript, just ignore a line is too much longer. You can break it after a comma or an operator, like:

document.getElementById("demo").innerHTML = "Hello World.";

Instead it you can write

document.getElementById("demo").innerHTML =

"Hello World.";

JavaScript's Code Blocks

We can execute multiple statements together to show a bulk information. This is done by writing the statements in a code block inside curly brackets.

For example.

<html>

<body>

<h2>JavaScript's Code Block</h2>

<p>To show the bulk information, it is used</p>

<button type="button" onclick="myFunction()">Click Me!</button>

function myFunction() {

document.getElementById("test1").innerHTML = "Hello World!";

document.getElementById("test2").innerHTML = "I am your new friend.";

}

</script>

</body>

</html>

Try it in editor:

Try it yourself editor


Code <html> <body> <h2>JavaScript's Code Block</h2> <p>To show the bulk information, it is used</p> <button type="button" onclick="myFunction()">Click Me!</button> <p id="test1"></p> <p id="test2"></p> <script> function myFunction() { document.getElementById("test1").innerHTML = "Hello World!"; document.getElementById("test2").innerHTML = "I am your new friend."; } </script> </body> </html>	Output

JavaScript Keywords

JavaScript statement often starts with a keyword to identify the action to be performed. These keywords are reserved words for JavaScript. Let's know some most usual keywords of JavaScript:

Keyword	Description
let	Assign a value inside a variable
var	Assign a variable inside a variable
const	Assign constant number or string(value cant be changed during execution)
if	Identify a block of statements to be executed on given condition
switch	Identify a block of statements to be executed in different cases
for	Identify a block of statements to be executed in a loop
function	Declares a function
return	Exits a function
try	Implements error handling to a block of statements