JAVASCRIPT IMPLEMENTATIONS
Though JavaScript and ECMAScript are often used synonymously, JavaScript is much more than just what is defined in ECMA-262. Indeed, a complete JavaScript implementation is made up of the following three distinct parts (see Figure 1-1):
FIGURE 1-1
- The Core (ECMAScript)
- The Document Object Model (DOM)
- The Browser Object Model (BOM)
ECMAScript
ECMAScript, the language defined in ECMA-262, isn't tied to web browsers. In fact, the language has no methods for input or output whatsoever. ECMA-262 defines this language as a base upon which more-robust scripting languages may be built. Web browsers are just one host environment in which an ECMAScript implementation may exist. A host environment provides the base implementation of ECMAScript and implementation extensions designed to interface with the environment itself. Extensions, such as the Document Object Model (DOM), use ECMAScript's core types and syntax to provide additional functionality...
