To FootJavascript and Java are different languages.
The language commonly called Javascript is essentially an implementation of ECMAScript.
The language Jscript is a Microsoft version of ECMAScript.
The current (2010) formal international standard for ECMAScript is ISO/IEC 16262:2002, which is in effect a corrected version of ECMA-262 3rd Edition. Both are freely available in PDF.
ECMA-262 4th Edition was abandoned. ECMA-262 5th Edition was released in December 2009. Although some browsers already implement parts of it, its general use on the open Web will be unsafe for some while after completion.
ECMA-262 includes a brief history of the language.
Wikipedia provides more detail; see references below. But remember that it may not be completely accurate.
ECMAScript provides full arithmetic on IEEE Doubles, logical operations on 32-bit integers, Booleans, objects with methods, arrays, strings with Regular Expressions, and the traditional range of flow control constructs.
ECMAScript itself provides no Input/Output facilities.
In use, a Javascript interpreting engine is therefore used with one of several environments or Document Object Models.
Browsers provide a standardised screen-and-keyboard interface, but do not give general disc access.
The HTML and CSS of Web pages also need to be standards-compliant; W3C provides checkers.
Material needed
In WSH, Javascript is an alternative to the more commonly used VBScript, with corresponding access to the Windows API.
Material needed
Much of the material in actual use on the Web, and in "tutorial" Web sites, is badly written and/or untrustworthy.