JavaScript syntax: Difference between revisions

Revision as of 04:02, 18 February 2006

Revision as of 12:25, 18 February 2006

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Variables declared outside of any function, and variables declared without the <code>var</code> statement, are in "global" scope, visible in the entire web page; variables declared inside a function with the <code>var</code> statement are local to that function.

To pass variables from one page to another, a developer can set a [[HTTP cookie|cookie]] or use a hidden frame or window in the backgrounduser's to store thembrowser. ThisMore approachcomplicated reliesweb onapplications thewill browseroften DOMstore ratherdata thanin anythinga inhidden theframe JavaScriptor language itself[[iframe]].

A third way to pass variables between pages is to include them in the call for the next page. The list of arguments, called the query string, is preceded by a question mark, and each argument specification follows the format: ''name=value''. The ampersand character is used as the list separator character. An example of this technique is ''<code>sample.html?arg1=foo&arg2=bar</code>''. The following page can then extract these values by performing [[regular expression]] operations on the <code>window.___location</code> property.

There is also an old [[hack]] that still works on most browsers: the '''window.name''' property can be set to string data which can then be retrieved by the next page to load into the window.