Some minor issues encountered when writing javascript _ javascript tips-js tutorial

Some minor issues encountered when writing JavaScript code. For more information, see. 1. When writing an OnClientClick event, add return; otherwise, OnClientClick returns false, but The OnClick event is still executed.
For example:

The Code is as follows:

2. open a new window in window. showModalDialog () mode. if it contains a js editor or another third-party editor, the editor cannot be edited;
So far, I have not found a better solution. I should try it in the window. open () mode.
3. All checkbox selections:
Html:

The Code is as follows:

Select All

Js:

The Code is as follows:

Function selectAll ()
{
Var obj = document. getElementById ("chkAll ");
Var ckblist = document. getElementById ("ckblist ");
Var chk = ckblist. getElementsByTagName ("input ");
If (obj. checked)
{
For (var I = 0; I <chk. length; I ++)
{
Chk [I]. checked = true;
}
}
Else
{
For (var I = 0; I <chk. length; I ++)
{
Chk [I]. checked = false;
}
}
}

Below are some basic js knowledge

The Code is as follows:

①
// Js retrieves the Table and changes its style