How to Retrive list items from SharePoint list using Java Script

Hi, I have a list name=  'Customer Link'.

And have the List columns:

Title:

Language:

URL:

I have to retrieve the "URL' list column value and need to display in the App Part, (SharePoint Hosted Apps) through java script.

Hi any help how to retrieve, I am new to coding, will u please help with entire code example.