How to Verify if the Page is in Edit Mode using JavaScript in SharePoint 2013

Having 5 years of experience with IT web technologies. I have been working on C# as my back end language and HTML5, CSS3, JavaScript, jQuery as front end development in Microsoft .net environment. I am currently working in Microsoft SharePoint technology, mainly focused on Branding stuffs. Very passionate about creative front end development and eager to learn new things about it. Somewhat I am gaming freak as well, specifically I am Valve Dota 2 fan.