JavaScript link(JSLink) is one of the new features introduced in the SharePoint 2013 to improve the client rendering. This is also one of the move by Microsoft to make everything works at client side.
Remember we used to change data view web part functionality in SharePoint designer 2010 for manipulating fields in the sharepoint list. Now in SharePoint 2013, we don't need to do that anymore. Let's get into the concept how it works.
Js Link - you can refer External JavaScript file to be used for the listview webpart
Steps:
1.Edit the site page
2. Edit the List view web part
3.Go to Miscellaneous section
3.See the attached file to check the new feature JSLink
4. Provide your JavaScript library link. It should be either in SiteAssets Document library or Master Gallery.
Happy SharePointing :-)