The control block in the middle is actually an IFRAME, which defines its width as 10.
Then, in his internal JS, control the left and right two IFRAME.
CopyCode The Code is as follows: function switchsysbar (){
If (parent.doc ument. getelementbyid ('attachucp'). Cols = "160,10 ,*"){
Document. getelementbyid ('leftbar'). style. Display = "";
Parent.doc ument. getelementbyid ('attachucp'). Cols = "0, 10 ,*";
}
Else {
Parent.doc ument. getelementbyid ('attachucp'). Cols = "160,10 ,*";
Document. getelementbyid ('leftbar'). style. Display = "NONE"
}
}
<frameset id = "attachucp" framespacing = "0" border = "0" frameborder = "no" Cols = "160,10, * "rows =" * "> <frame scrolling =" yes "noresize frameborder =" no "name =" leftframe "src =" test.html "> <frame id =" leftbar "scrolling = "no" noresize name = "switchframe" src = "swich.html"> <frame scrolling = "yes" noresize border = "0" name = "mainframe" src = "http://www.jb51.net"> </frameset>
[Ctrl + A select all Note: To introduce external JS, refresh it before execution]