November 2001
Intermediate to advanced
936 pages
68h 43m
English
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Embedding JavaScript in HTML
Client-side JavaScript code is embedded within HTML documents in a number of ways:
Between a pair of
<script>and</script>tagsFrom an external file specified by the
srcattribute of a<script>tagIn an event handler, specified as the value of an HTML attribute such as
onclickoronmouseoverAs the body of a URL that uses the special
javascript:protocol
The following sections document each of these JavaScript embedding techniques in more detail. Together, they explain all the ways to include JavaScript in web pages -- that is, they explain the allowed structure of JavaScript programs on the client side.
The <script> Tag
Client-side
JavaScript scripts are part of an HTML file and are coded within
<script>
and </script> tags. You may place any number
of JavaScript statements between these tags; they are executed in
order of appearance, as part of the document loading process.
<script> tags may appear in either the
<head> or <body> of
an HTML document.
A single HTML document may contain
any number of nonoverlapping pairs of
<script> and
</script> tags. These multiple, separate scripts are executed in the order in which they appear within the document. While separate scripts within a single file are executed at different times during the loading and parsing of the HTML file, they constitute part of the same JavaScript program: functions and variables defined in one script are available to all scripts that follow in the same file. For example, ...