what does !sessionStorage.function do? code example

Example 1: javascript sessionStorage

var setsession = window.sessionStorage.setItem("animals", "cat");
	var getsession = window.sessionStorage.getItem("animals");
	console.log(getsession);

Example 2: sessionstorage

sessionStorage is like localStorage
except that it is cleared when the page session ends meaning when you close 
your chrome tab or any other browser tab

usage methods

// Save data to sessionStorage
sessionStorage.setItem('key', 'value');

// Get saved data from sessionStorage
let data = sessionStorage.getItem('key');

// Remove saved data from sessionStorage
sessionStorage.removeItem('key');

// Remove all saved data from sessionStorage
sessionStorage.clear();

Example 3: what is sessionStorage

sessionStorage is like localStorage
except that it is cleared when the page session ends 
		— that is, when the page is closed.