Javascript is used as client side scripting
language.it adds interactive features to
a web page. It is used for validate purpose.
There are two types of validation :
1.
client side validation.
2.
Server side validation
Client side is done at browser. For to
limit the user age as 18 we can done at browser. But for example to check no of
books available you have check database such this need server side validation.
To run java script different browsers
use different engines. For example chrome use v8 and Mozilla use spider monkey
engines
Now a day visual studio code is a
popular editor for javascript.
The notes are below are taken from Wikipedia
A JavaScript
engine is a computer program that executes JavaScript (JS) code. The
first JavaScript engines were mere interpreters, but all relevant modern
engines use just-in-time compilation for improved performance.
JavaScript engines are typically
developed by web browser vendors, and every major browser has one. In a
browser, the JavaScript engine runs in concert with the rendering engine via
the Document Object Model.
The use of JavaScript engines is not
limited to browsers. For example, the Chrome V8 engine is a core component of
the popular Node.js and Deno runtime systems.
Since ECMAScriptt (ES) is the
standardized specification of JavaScript, ECMAScript engine is another name for these engines.
Index.html
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
<script src="./script.js"></script>
</head>
<body>
<h1>welcome</h1>
</body>
</html>
Script .js
console.log("welcome to javascript code by karthikeyan and mukesh");
script is a keyword used
to denote java script code. In index.html we mention that source file of script
is script.js.
in the above program script,js and index.html are residing at same location.
Now a day Java script
is used for server side validation also. We have to install node.js for that
purpose.
To run the above
program copy path of index.html in vs
code editor.in browsers address bar simply paste it .
To see the result of
console.log statement in browser press f12 short cut key.
Click console tab and
see the results.
We can use node
command to run the javascript program directly with out embedding with html
program.
To get into terminal
in vs code editior
Short cut key is ctrl+~
The ~ symbol is below
esc key at keyboard.
To run script.js file just type the following line at terminal
Node script.js
-will continue
By Muthukarthikeyan
Contact :919629329142.
