JavaScript Statements - JavaScript Tutorial

What are JavaScript Statements?

JavaScript statements are commands that tells the browser what to do. They are the building blocks of JavaScript code and are executed in the order they are written. Statements often end with a semicolon (;), although it’s not always mandatory.

Assigment Statement

An assignment statement assigns a value to a variable.

let x = 10;

JavaScript
​x
 
let x = 10;

Function Call Statement

A function call statement invokes a function.

alert("Hello, World!");

JavaScript
 
alert("Hello, World!");

Conditional Statement

A conditional statement executes code based on a condition.

if (x > 5) {
    console.log("x is greater than 5");
}

JavaScript
 
if (x > 5) {    console.log("x is greater than 5");}

Loop Statement

A loop statement repeats a block of code as long as a specified condition is true.

for (let i = 0; i < 5; i++) {
    console.log("Number " + i);
}

JavaScript
 
for (let i = 0; i < 5; i++) {    console.log("Number " + i);}

JavaScript Code Blocks

A code block is a group of statements enclosed in curly braces {}. It is often used with control structures like if statements and loops to execute multiple statements.

{
    let x = 10;
    let y = 20;
    let sum = x + y;
    console.log("The sum is " + sum);
}

JavaScript
 
{    let x = 10;    let y = 20;    let sum = x + y;    console.log("The sum is " + sum);}

JavaScript Statements Example Code

Explanation of Code:

Assignment Statement: Assigns the value 10 to the variable x.
Function Call Statement: Displays an alert box with the value of x.
Conditional Statement: Checks if x is greater than 5 and logs a message if true.
Loop Statement: Logs numbers 0 to 4 to the console.
Code Block: Declares variables y and sum, calculates the sum of x and y, and logs the result.

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>JavaScript Statements Example</title>
</head>
<body>
    <script>
        // Assignment statement
        let x = 10;

        // Function call statement
        alert("The value of x is " + x);

        // Conditional statement
        if (x > 5) {
            console.log("x is greater than 5");
        }

        // Loop statement
        for (let i = 0; i < 5; i++) {
            console.log("Number " + i);
        }

        // Code block
        {
            let y = 20;
            let sum = x + y;
            console.log("The sum of x and y is " + sum);
        }
    </script>
</body>
</html>

JavaScript
 
<!DOCTYPE html><html lang="en"><head>    <meta charset="UTF-8">    <meta name="viewport" content="width=device-width, initial-scale=1.0">    <title>JavaScript Statements Example</title></head><body>    <script>        // Assignment statement        let x = 10;​        // Function call statement        alert("The value of x is " + x);​        // Conditional statement        if (x > 5) {            console.log("x is greater than 5");        }​        // Loop statement        for (let i = 0; i < 5; i++) {            console.log("Number " + i);        }​        // Code block        {            let y = 20;            let sum = x + y;            console.log("The sum of x and y is " + sum);        }    </script></body></html>