How to show confirmation alert before closing browser tab using JavaScript
Implementation : Add the below given script in head section of page (webform, Html). < script type ="text/javascript"> window.onbeforeunload = function () { return 'Please save the changes before close the tab !!!' ; } </ script > Complete HTML Markup of webform : < html xmlns ="http://www.w3.org/1999/xhtml"> < head runat ="server"> < script type ="text/javascript"> window.onbeforeunload = function () { return 'Please save the changes before close the tab !!!' ; } </ script > </ head > < body > < form id ="form1" runat ="server"> < div > < fieldset > < legend > JavaScript Example </ legend > < h1 > Show confirmation alert before closing browser tab using JavaScript </ h1 > </ fieldse