localStorage实现便签小程序

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。

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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+='<div><button class="btn btn-success"'+'type="button" id="dropdownMenu" onclick="show(this)"><div class="col-md-4"><img src='+mess.icon+' class="img-circle size" id="userpic"><br><font style="text-align:center">'+mess.name+'</font></div><div class="col-md-8"><h2>'+json[i].headle+'</h2><font>'+json[i].date+'</font></div><span class="caret" style="margin-top:50px;">'+'</span></button><p style="display:none">'+json[i].diary+'</p><div>'; 
        }

    }
}

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