Enclosure and unboxing of value types in JScript

Js|jscript

The Expando property of an object in JScript is an important means of adding a member to a reference type such as Object,array, but this is not the case for a value type, such as
var str = "string1";
Str.method1 = function () {
Do something
};

STR.METHOD1 ();//There will be an error, the error message (I forgot) is that STR does not exist in this method

Such a statement would not run, and in C # programming a value type has a boxing and unboxing operation to convert it to a reference type, and for that, there are value types in JScript, and we can do a similar operation, which is implemented as follows, where the operation of Tojson () is shown here, The purpose is to represent objects (generic) in strings, so that the object can be restored using the Eval function.
Boolean.prototype.box = function () {
Return to New Boolean (this);
};
Number.prototype.box = function () {
Return to new number (this);
};
String.prototype.box = function () {
Return a new String (this);
};
Boolean.prototype.unbox = function () {
Return eval (This.tojson ());
};
Number.prototype.unbox = function () {
Return eval (This.tojson ());
};
String.prototype.unbox = function () {
Return eval (This.tojson ());
The};box is the packing, the unbox is the unpacking. The test code is as follows:
str = True.box ();
alert (str);
str = Str.unbox ();
alert (str); so we have a boxed operation in JScript, what's the benefit? Take a look at the beginning of the sentence, at this time we can treat String,boolean,number as the object of the three types of value, you can at run time for the variable value type of the Expando property, this is not convenient?
And the unboxing operation is also very simple, only need to call the similar str.unbox () to be done.