One of the nice things about using JavaScript, is that you don't need any special tools - just a text editor or word processor (be sure you save in text only or ASCII mode) and a Web browser. There are shareware text editors which are helpful, because they do syntax coloring (key words for HTML are in different color from text strings) and in some cases save to FTP (allows to save directly to Web server). Additionally, you can use HTML editors, which often feature specific help in creating JavaScript (pull down menus, for example, for common functions).

• BBEdit Excellent editor for MacOS (commercial and free versions)
  
• NoteTab Pro Powerful Windows text editor (shareware - $9)
• Textpad Good text editor from Helios Software
• FrontPage Popular HTML editor from Microsoft, avaialble for Windows and MacOS (commercial)
• Dreamweaver Excellent HTML editor for Windows and MacOS; helpful JavaScript functionality (commercial)

There are a great many sources of information on the Web about JavaScript, inculding some excellent on-time tutorials. There are plenty of books as well, but make sure you get one that's up to date, since JavaScript functionality changes each time a new browser generation is born.

• Netscape JavaScript Guide Complete reference source for JavaScript; includes examples
• JavaScript for the Total Non-Programmer Very good on-line tutorial (from webteacher)
• Script Writing 101 Another well put-together JavaScript tutorial (from techweb)
• Curso de JavaScript Tutorial in Spanish

If you've gotten comfortable with the basics of JavaScript, you might be interested in taking a look at DHTML, or dynamic HTML, which is implement in the latest versions of Web browsers from Netscape and Microsoft. DHTML uses style sheets and scripting (in JavaScript or VBScript) to enable on-the-fly changes to Web pages elements (change in color of headers, image sources, etc in response to user actions).

• Dymanic HTML Index Good starting point for learning about DHTML
• Web Style Sheets Official Info on style sheets from W3C, the official Web standards organization
• Dynamic HTML Lab Good source of info and examples (from Webreference)