SharePoint JavaScript JSON

I have a API URL which gives a JSON file. I want to read the JSON and manipulate the data and write it in SharePoint List. From a page it should able to pass a variable to get the data from the json file[URL].I was able to create list items using JavaScript and Inserted the data from the JSON file. I need some minor work to create, update and delete operation. I definitely recommend someone with SharePoint environment to work. Thanks