<input type="text">
    <button class="set">存储数据</button>
    <button class="get">获取数据</button>
    <button class="remove">删除数据</button>
    <button class="del">清空所有数据</button>

        var ipt = document.querySelector(‘input‘)
        var set = document.querySelector(‘.set‘)
        var get = document.querySelector(‘.get‘)
        var remove = document.querySelector(‘.remove‘)
        var del = document.querySelector(‘.del‘)
        set.addEventListener(‘click‘, function () {
            var val = ipt.value;
            sessionStorage.setItem(‘uname‘, val)
            sessionStorage.setItem(‘pwd‘, val)
        })
        get.addEventListener(‘click‘, function () {
            console.log(sessionStorage.getItem(‘uname‘));
        })
        remove.addEventListener(‘click‘, function () {
            sessionStorage.removeItem(‘uname‘)
        })
        del.addEventListener(‘click‘, function () {
            sessionStorage.clear()
        })

var ipt = document.querySelector(‘input‘)
        var set = document.querySelector(‘.set‘)
        var get = document.querySelector(‘.get‘)
        var remove = document.querySelector(‘.remove‘)
        var del = document.querySelector(‘.del‘)
        set.addEventListener(‘click‘, function () {
            var val = ipt.value;
            localStorage.setItem(‘username‘, val)
            localStorage.setItem(‘pwd‘, val)
        })
        get.addEventListener(‘click‘, function () {
            console.log(localStorage.getItem(‘username‘));
        })
        remove.addEventListener(‘click‘, function () {
            localStorage.removeItem(‘username‘)
        })
        del.addEventListener(‘click‘, function () {
            localStorage.clear()
        })

<input type="text" id="username"><input type="checkbox" id="remember">记住用户名

 1 var username = document.querySelector(‘#username‘)
 2     var remember = document.querySelector(‘#remember‘)
 3     if (localStorage.getItem(‘username‘)) {
 4         username.value = localStorage.getItem(‘username‘)
 5         remember.checked = true;
 6     }
 7     remember.addEventListener(‘click‘, function () {
 8         if (this.checked) {
 9             localStorage.setItem(‘username‘, username.value)
10         } else {
11             localStorage.removeItem(‘username‘)
12         }
13     })