Some Problems in Javascript inheritance

The inheritance class of JavaScript has been said to be rotten. Its core is to run the parent class A () in subclass B ().

A concise implementation:

1. Function B (arg1, arg2) // assume that subclass B has two initial values, in which arg1 is passed to parent Class
2. {
3. // Inherit
4. A. Call (this, arg1); // assume that parent class A has an initial value.
5. }

I recently found some problems with function inheritance,

See the following:

Suppose:

1. Function A (arg1)
2. {
3. This. M1 = arg1;
4. This. ocap = Document. getelementbyid (arg1 );
6. This. ocap. onmousedown = This. capturemouse (this );
8. }
10. // Define a member function externally
12. A. Prototype. capturemouse = function (othis)
13. {
14. Return function ()
15. {
16. Othis. ocap. setcapture (true );
17. }
18. }

At this time, a () itself runs well.

However, when B () inherits a, the interpreter cannot interpret capturemouse.

When running a in B (), the interpreter interprets a in sequence, so a. Prototype. capturemouse is not found.

After the code is changed to the following,

Solution:

1. Function A (arg1)
2. {
3. This. M1 = arg1;
4. This. ocap = Document. getelementbyid (arg1 );
5. // Define the capturemouse function first
6. This. capturemouse = function (othis)
7. {
8. Return function ()
9. {
10. Othis. ocap. setcapture (true );
11. }
12. }
13. // Apply capturemouse again
14. This. ocap. onmousedown = This. capturemouse (this );
15. }