Bookmarklet

From Free Speech Wiki

A bookmarklet is an applet, a small computer application, stored as the URL of a bookmark in a web browser or as a hyperlink on a web page. The term is a portmanteau of the terms bookmark and applet.

Whether bookmarklet utilities are stored as bookmarks or hyperlinks, they are designed to add one-click functionality to a browser or web page. When clicked, a bookmarklet performs some function, one of a wide variety such as a search query or data extraction. Usually the applet is a JavaScript program.

[edit] Concept

Web browsers use URIs for the href attribute of the <A> tag and for bookmarks. The first part of the URI, such as http:, file:, or ftp:, specifies the protocol and required form for the rest of the string. Browsers also implement a prefix javascript: that to a parser is just like any other URI. Internally, the browser sees that the protocol is javascript, treats the rest of the string as javascript code which is then executed, and uses the resulting string as the new page.

The executing script has access to the current page, which it may inspect and change. If the script returns an undefined type rather than a string, the browser will not load a new page, with the result that the script simply runs against the current page content. This permits in-place font size and color changes, for example, without a page reload.

[edit] Usage

Bookmarklets are saved and used as normal bookmarks. As such, they are simple "one-click" tools which add functionality to the browser. For example, they can:

Modify the appearance of a web page within the browser (e.g., change font size, background color, etc.).
Extract data from a web page (e.g., hyperlinks, images, text, etc.).
Query a search engine, with search term(s) provided by previously selected text, or by a dialog box.
Submit the current page to a link validation service, or translation service.
Set commonly chosen configuration options when the page itself provides no way to do this.

"Installation of a bookmarklet" is performed by creating a new named bookmark in the toolbar, following the browser's procedure, and pasting the code into the URL destination field. The bookmarklet can then be run by loading the bookmark normally.

[edit] History

Steve Kangas of www.bookmarklets.com coined the term "bookmarklet," which he started to create based on an idea suggested in the Netscape JavaScript Guide. The term favelet was used early on by Tantek Çelik on 6 September 2001 (personal email). Brendan Eich, who developed JavaScript at Netscape, gave this account of the origin of bookmarklets:

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