javascript

Chapter 22: The Evolution of JavaScript
There are four built - in namespaces, as follows:
❑
❑
❑
❑
__ES4__
intrinsic
iterator
meta
The __ES4__ namespace is the global namespace for ECMAScript 4 and is always in use. The
instrinsic namespace is used to define internal properties or methods that should not be accessible in
normal scripts. You will mostly likely never use or reference the instrinsic namespace. The iterator
namespace is used specifically for methods and classes related to iterators. You ’ ve already seen the use
of the meta namespace in defining catchall getters and setters on dynamic classes; it ’ s used for system
protocols and cannot be extended by developers.
You can use a particular namespace by default via the use namespace directive, as shown here:
namespace version1_0;
namespace version1_5;
version1_0 function log(msg: String){
alert(msg);
}
version1_5 function log(msg: String){
console.log(msg);
}
use namespace version1_0;
//calls version1_0 log();
log(“Hello world!”);
//calls version 1_5 log();
version1_5::log(“Hello world!”);
This code defines two namespaces: version1_0 and version 1_5 . Each namespace has a function
defined called log() . In the default namespace, there is no definition for log() , so you must either use
a namespace via use namespace to set it as the default or use the namespace as a qualifier followed by
:: and then the function name.
As with everything in ECMAScript, namespaces are also objects.
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