Javascript how to and where to
how to put a javascript into an HTML page
how to handle simple browsers
where to put the javascript
using an external javascript
How to put a javascript into an HTML page
<html>
<body>
<script type="text/javascript">
document.write("Hello world");
</script>
</body>
</html>
<html>
<body>
<script type="text/javascript">
document.write("Happy, Happy,Joy,Joy");
</script>
</body>
</html>
to add HTML tags to the javascript
<html>
<body>
<script type="text/javascript">
document.write("<h1>Hello World</h1>");
</script>
</body>
</html>
<html>
<body>
<script type="text/javascript">
document.write("<h1>Happy, Happy,Joy,Joy</h1>");
</script>
</body>
</html>
To insert a javascript into an HTML page, we use the <script> tag.
Inside <script> tag we use the type attribute to define the scripting language.
<script type="text/javascript"> and </script> tell where the javascript starts and end
<html>
<body>
<script type="text/javascript">
....
</script>
</body>
</html>
The document.write command is a standard javascript command for writing output to a page.
<html>
<body>
<script type="text/javascript">
document.write("<h1>Hello World</h1>");
</script>
</body>
</html>
How to handle simple browsers
Browsers that do not support javascript will display javascript as page content.
to prevent them from doing this and as a part of the javascript standard, the HTML comment tag should be used to "hide" the javascript.
<html>
<body>
<script type="text/javascript">
<!--
document.write("<h1>Hello World</h1>");
//-->
</script>
</body>
</html>
The two forward slashes at the end of comment line(//) comprise the javascript comment symbol.
This prevents javascriptfrom from exicuting the --> tag.
where to put the javascript
javascript in a page will be executed immediately while the page loads into the browser.
Scripts in <head>
scripts to be executed when they are called, or when an event is triggered, are placed in functions.
<html>
<head>
<script type="text/javascript">
function message()
{
alert("this alert box was called with the onload event");
}
</script>
</head>
<body onload="message()">
</body>
</html>
Scripts in <body>
If you don't want your script to be placed inside a function, or if your script should write page content,
it should be placed in the body section.
<html>
<head>
</head>
<body>
<script type="text/javascript">
document.write("this message is written by javascript");
</script>
</body>
</html>
Scripts in <head> and <body>
<html.
<head>
<script type="text/javascript">
function message()
{
alert("This alert box was called with the onload event");
}
</script>
</head>
<body onload="message()">
<script type="text/javascript">
document.write("This message is written by javascript");
</script>
</body>
</html>
Using an External Javascript
If you want to ru n the same javascript on several pages without having to write the same script on every pag,
You can write a javascript in an eternal file.
save the external file with a .js file extension
Note: The external script file cannot contain the <script> tag
<html>
<head>
<script type="text/javascript" src="xxx.js"></script>
</head>
<body>
</body>
</html>
how to put a javascript into an HTML page
how to handle simple browsers
where to put the javascript
using an external javascript
How to put a javascript into an HTML page
<html>
<body>
<script type="text/javascript">
document.write("Hello world");
</script>
</body>
</html>
<html>
<body>
<script type="text/javascript">
document.write("Happy, Happy,Joy,Joy");
</script>
</body>
</html>
to add HTML tags to the javascript
<html>
<body>
<script type="text/javascript">
document.write("<h1>Hello World</h1>");
</script>
</body>
</html>
<html>
<body>
<script type="text/javascript">
document.write("<h1>Happy, Happy,Joy,Joy</h1>");
</script>
</body>
</html>
To insert a javascript into an HTML page, we use the <script> tag.
Inside <script> tag we use the type attribute to define the scripting language.
<script type="text/javascript"> and </script> tell where the javascript starts and end
<html>
<body>
<script type="text/javascript">
....
</script>
</body>
</html>
The document.write command is a standard javascript command for writing output to a page.
<html>
<body>
<script type="text/javascript">
document.write("<h1>Hello World</h1>");
</script>
</body>
</html>
How to handle simple browsers
Browsers that do not support javascript will display javascript as page content.
to prevent them from doing this and as a part of the javascript standard, the HTML comment tag should be used to "hide" the javascript.
<html>
<body>
<script type="text/javascript">
<!--
document.write("<h1>Hello World</h1>");
//-->
</script>
</body>
</html>
The two forward slashes at the end of comment line(//) comprise the javascript comment symbol.
This prevents javascriptfrom from exicuting the --> tag.
where to put the javascript
javascript in a page will be executed immediately while the page loads into the browser.
Scripts in <head>
scripts to be executed when they are called, or when an event is triggered, are placed in functions.
<html>
<head>
<script type="text/javascript">
function message()
{
alert("this alert box was called with the onload event");
}
</script>
</head>
<body onload="message()">
</body>
</html>
Scripts in <body>
If you don't want your script to be placed inside a function, or if your script should write page content,
it should be placed in the body section.
<html>
<head>
</head>
<body>
<script type="text/javascript">
document.write("this message is written by javascript");
</script>
</body>
</html>
Scripts in <head> and <body>
<html.
<head>
<script type="text/javascript">
function message()
{
alert("This alert box was called with the onload event");
}
</script>
</head>
<body onload="message()">
<script type="text/javascript">
document.write("This message is written by javascript");
</script>
</body>
</html>
Using an External Javascript
If you want to ru n the same javascript on several pages without having to write the same script on every pag,
You can write a javascript in an eternal file.
save the external file with a .js file extension
Note: The external script file cannot contain the <script> tag
<html>
<head>
<script type="text/javascript" src="xxx.js"></script>
</head>
<body>
</body>
</html>