To Do List: [item 1, item 2, item 3] -> Tasks
"Take out trash" -> button
"delta" change -> act among button, tasks, Local Storage and output
F12 to inspect the code
Local Storage -> file -> key and value
key -> tasks_10, value -> Take out trash|Walk the dog|Feed the cat
F12 -> Elements
Library is used as a source by "main" code
https://www.w3schools.com/jsref/event_onclick.asp