localStorage javascript

;(function (window, document, undefined) {
    // Feature test for localStorage
    if(!('localStorage' in window)) return;
    // Get links
    var localLinks = localStorage.getItem('go--links');
    if (!localLinks) return;
    // The action
    var userButton = document.getElementById('button-user');
    userButton.classList.remove('hidden');
})(window, document);   

Three methods:

localStorage.setItem('global--night-mode', true);
localStorage.getItem('global--night-mode');
localStorage.removeItem('global--night-mode');

localStorage only supports strings. Use JSON.stringify() and JSON.parse().

var names = [];
names[0] = prompt("New member name?");
localStorage.setItem("names", JSON.stringify(names));

//...
var storedNames = JSON.parse(localStorage.getItem("names"));