Difference between revisions of "JavaScript"
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| − | * Variable scope : only two, local and global. | + | * Variable scope : only two, local and global. No block scope! |
| + | * Local variables belong to the defined function. | ||
| + | * Global variables belong to the global object. In web pages, the global object is ''window''. | ||
Revision as of 04:14, 6 December 2012
Intro
- JS is a cross-platform object oriented scripting language.
- Is designed for easy embedding in other products and applications, such as web browsers.
- Core JS consists of a set of objects e.g. Array, Date and Math and language elements such as operators and control structures.
- Client-side JavaScript extends the core language by supplying objects to control a browser and its Document Object Model (DOM). e.g, client-side extensions allow an application to place elements on an HTML form and respond to user events such as mouse clicks, form input, and page navigation.
- JS as opposed to say, Java, is loosely typed.
Values, Variables and Literals
- JS is dynamically typed. So, the following is possible:
var ans = 42;
ans = "Forty two";
- Variable scope : only two, local and global. No block scope!
- Local variables belong to the defined function.
- Global variables belong to the global object. In web pages, the global object is window.
