how to close the child window when closing parent window in javascript?

Question

How to close the child window when closing parent window in javascript?

Solution

If by parent and child windows you mean a pop-up window and the window that opened it, you can't do exactly this, but the following script in the main window will close the pop-up window when the main window is unloaded (i.e. either closed or the user navigates to another page or refreshes):

var popUp = window.open("popup.html", "popup", "width=300,height=200");

window.onunload = function() {
    if (popUp && !popUp.closed) {
        popUp.close();
    }
};

Historical note: it used to be possible to do this in some browsers (e.g. Firefox) by using the dependent window property in the third parameter of the window.open call (e.g. var popUp = window.open("popup.html", "popup", "width=300,height=200,dependent");) but according to quirksmode it's no longer supported in anything. I haven't tested this myself.