Bookmarklets, useful javascript programs

          Each bookmarklet is a tiny program (a JavaScript application) contained in a bookmark (the URL is a "javascript:" URL) which can be saved and used the same way you use normal bookmarks. They add one-click functionality to a browser or web page. They are different from extensions installed in a web browser. The idea was suggested in the Netscape JavaScript Guide.

Bookmarklets are free:
          There is a limited amount of room in a bookmark URL field. Most of the famous browsers allow URL size less than 2000 characters. They may produce error after that. Read more about URL size limit here. This means that each bookmarklet is much simpler than a traditional program. They are usually two or three lines of code.

Are bookmarklets safe?
          Bookmarklets are safer than traditional software for the following reasons:

1. They are less error prone to syntax and logical mistakes as they are very small.
2. No separate software installation is required to run them.
3. Your hard drive is protected by JavaScript security restrictions imposed on bookmarklets.
4. If something goes wrong (e.g. Using a Netscape-only bookmarklet on Internet Explorer) the worst thing that is likely to happen is to get a JavaScript error message.

Browser requirement for running bookmarklet:
          Bookmarklets require Netscape 3, Explorer 4, Mozilla Firefox 2 (or later versions of these browsers) with JavaScript enabled. Any other browser supporting java script will also do.

Usage of bookmarklet:

          Bookmarklets are simple one click tools which add functionality to the browser. For example, they can:

1. Modify font size, background color of web page
2. Extract data from a web page (e.g., hyperlinks, images, text, etc.)
3. Query a search engine.
4. Submit the current page to a link validation service, or translation service.
5. Set commonly chosen configuration options when the page itself provides no way to do this.

Sample bookmarklets:

1. SideWiki bookmarklet: SideWiki is released by Google on . You can install Google toolbar with SideWiki from http://www.google.com/sidewiki/intl/en/index.html. Browsers get updated regularly so you can not guarantee that SideWiki functionality in Google toolbar will work on updated beta version of your browser. Click here to see and write SideWikis for this page. You need to sign in your gmail account for writing a SideWiki. I have already written first SideWiki to demonstrate functionality.
2. Rapidshare.com hack bookmarklet: Open your rapidshare.com .Then click on free user. As soon as timer start type javascript:alert(c=0) in adress bar and press enter. A pop up message will come. Click ok and start downloading file without waiting.
3. See 0^th link in a web page: javascript:alert(document.links[0].href). 0^th link is the 1^st link which a search engine bot finds while parsing that page. You can find 5^th link on page by substituting 4 in place of 0 in booklet code.
4. Simple Firefox Notepad: Notepad (default size: 450x350) and Notepad (default size: 550x700)
5. Edit this web page: Edit this web page. Click at any point on web page and start editing (insert characters, delete characters etc.). After running above bookmarklet, text links become unclickable. Only flashes and hyper linked images can be clicked. You can always save edited page with 'Save As' option. This is very similar to writing a post for your website in Compose mode. Hit reload to get rid of the effect.
6. Crazy images: Crazy images. This bookmarklet will scoop up all the images on the web page and have them start spiraling around. Again Hit refresh to stop images spiraling.

Get more bookmarklet:
          Following sites contain number of useful bookmarklets.

1. http://www.marklets.com/bookmarklets
2. https://www.squarefree.com/bookmarklets
3. http://mozilla.gunnars.net/bookmarklets/trans-how-to.html
4. http://www.7is7.com/software/bookmarklets/notepad.html

References:

• http://en.wikipedia.org/wiki/Bookmarklet
• http://www.bookmarklets.com

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