Javascript
JavaScript Program
A JavaScript program is a collection of programming statements which contain the instructions that need to be executed.
JavaScript Statements contain keywords, operators, values, expressions, and comments.
Use of Semicolons: Semicolons are used to separate the JavaScript statements.
Example:
P= 8;
Q = 10;
You can specify multiple statements in one line separated by semicolons.
P= 8; Q = 10;
JavaScript White Space: You can include white spaces to the JavaScript code to make it easily readable. However, JavaScript doesn’t acknowledge multiple spaces.
JavaScript Line Breaks: It is advised to break the JavaScript statements following an operator, if they fit properly in one line.
Example:
document.getElementById("demo").innerHTML =
"Introduction to JavaScript"
JavaScript Code Blocks: Always group the JavaScript statements in the curly brackets . The statements mentioned in the code block run together. Generally code blocks are found in JavaScript functions.
Example:
function myFunction() {
document.getElementById("demo1").innerHTML = "Introduction to JavaScript ";
document.getElementById("demo2").innerHTML = "Let’s learn";
}
JavaScript Keywords: Some of the most-commonly used JavaScript keywords are as follows:
| Var | Declares a variable | | --------------------------- | ----------------------------------------------------------------- | | Let | Declares a block variable | | Const | Declares a block constant | | If | Specifies a block of statements to be executed on a condition | | Switch | Specifies a block of statements to be executed in different cases | | For | Specifies 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 |
JavaScript Print: JavaScript doesn’t offer print methods, thus you cannot access the output devices.
Use the window.print( ) to print the contents of the current window.
Example:
<!DOCTYPE html>
<html>
<body>
<button onclick="window.print()">Print this page</button>
</body>
</html>