前言：今天写了个小练习，把这几天看的东西巩固一下，在这个程序中用到了localStorage存储和json串的转换。

下面是具体的实现代码：

(1)首先判断是否存在用户，从而显示相应的界面

function isUser()

{

var storage = window.localStorage;

if (storage.user != undefined)

{

document.getElementById("showmess").style.display = "block";

document.getElementById("fillmess").style.display = "none";

}

else

{

document.getElementById("showmess").style.display = "none";

document.getElementById("fillmess").style.display = "block";

}

}

(2)存储用户信息

var pic; //全局变量存储图片信息

/*从本地电脑获得图片*/

function add_files(files) {

if (files.length) {

var file = files[0];

var reader = new FileReader();

reader.onload = function(e) {

document.getElementById("userpic").src = e.target.result;

pic = e.target.result;

}

reader.readAsDataURL(file);

}

}

function saveUserMess()

{

var name = document.getElementById("username").value;

if (name != "")

{

var storage = window.localStorage;

var jsonObj = {

name:name,

icon:pic

};

var user = JSON.stringify(jsonObj);

storage.setItem("user",user);

}

else

{

alert("昵称不为空");

}

}

(3)用户输入便签内容，并保存

function save_diary()

{

var headle = document.getElementById("headle").value;

var cont = document.getElementById("diary").value;

if (headle != "" && cont != "")

{

var storage = window.localStorage;

if (storage.diary != undefined)

{

var diary = storage.getItem("diary");

var jsonObj = JSON.parse(diary);

var diaryItem = {

headle:headle,

diary:cont,

date:new Date()

};

jsonObj.push(diaryItem);

var data = JSON.stringify(jsonObj);

storage.setItem("diary",data);

}

else

{

var jsonObj = [{

headle:headle,

diary:cont,

date:new Date()

}];

var diary = JSON.stringify(jsonObj);

storage.setItem("diary",diary);

}

}

else

{

alert("标题和内容不为空哦");

}

}

(4)将用户便签信息显示在见面

function showDiary()

{

var storage = window.localStorage;

var mess = JSON.parse(storage.user);

if (storage.diary != undefined)

{

var json = JSON.parse(storage.diary);

var div_id = document.getElementById("diarymess");

for (var i = 0; i < json.length; i++)

{

div_id.innerHTML+='