Web Storage是HTML5引入的一个非常重要的功能,可以在客户端本地存储数据,类似HTML4的cookie,但可实现功能要比cookie强大的多,cookie大小被限制在4KB,Web Storage官方建议为每个网站5MB。
Web Storage又分为两种:
- sessionStorage
- localStorage
从字面意思就可以很清楚的看出来,sessionStorage将数据保存在session中,浏览器关闭也就没了;而localStorage则一直将数据保存在客户端本地;
不管是sessionStorage,还是localStorage,可使用的API都相同,常用的有如下几个(以localStorage为例):
- 保存数据:localStorage.setItem(key,value);
- 读取数据:localStorage.getItem(key);
- 删除单个数据:localStorage.removeItem(key);
- 删除所有数据:localStorage.clear();
- 得到某个索引的key:localStorage.key(index);
如上,key和value都必须为字符串,换言之,web Storage的API只能操作字符串。
接下来,我们通过Web Storage开发一个简单的通讯录小程序,以演示相关API的使用方法;我们要实现如下功能:
- 录入联系人,联系人有姓名、手机号码2个字段,以手机号作为key存入localStorage;
- 根据手机号码,查找机主;
- 列出当前已保存的所有联系人信息;
首先,准备一个简单的HTML页面,如下:
- nbsp;HTML>
- html>
- head>
- meta charset="utf-8"/>
- title>HTML5本地存储之Web Storage篇title>
- head>
- body>
- div style="border: 2px dashed #ccc;width:320px;text-align:center;">
- label for="user_name">姓名:label>
- input type="text" id="user_name" name="user_name" class="text"/>
- br/>
- label for="mobilephone">手机:label>
- input type="text" id="mobilephone" name="mobilephone"/>
- br/>
- input type="button" onclick="save()" value="新增记录"/>
- hr/>
- label for="search_phone">输入手机号:label>
- input type="text" id="search_phone" name="search_phone"/>
- input type="button" onclick="find()" value="查找机主"/>
- p id="find_result">br/>p>
- div>
- br/>
- div id="list">
- div>
- body>
- html>
<meta charset="utf-8"> <title>HTML5本地存储之Web Storage篇</title> <div style="border: 2px dashed #ccc;width:320px;text-align:center;"> <label for="user_name">姓名:</label> <input type="text" id="user_name" name="user_name" class="text"> <br> <label for="mobilephone">手机:</label> <input type="text" id="mobilephone" name="mobilephone"> <br> <input type="button" onclick="save()" value="新增记录"> <hr> <label for="search_phone">输入手机号:</label> <input type="text" id="search_phone" name="search_phone"> <input type="button" onclick="find()" value="查找机主"> <p id="find_result"><br></p> </div> <br> <div id="list"> </div>
要实现联系人的保存,只需要简单实现如下JS方法即可:
- //保存数据
- function save(){
- var mobilephone = document.getElementById("mobilephone").value;
- var user_name = document.getElementById("user_name").value;
- localStorage.setItem(mobilephone,user_name);
- }
//保存数据 function save(){ var mobilephone = document.getElementById("mobilephone").value; var user_name = document.getElementById("user_name").value; localStorage.setItem(mobilephone,user_name); }
- //查找数据
- function find(){
- var search_phone = document.getElementById("search_phone").value;
- var name = localStorage.getItem(search_phone);
- var find_result = document.getElementById("find_result");
- find_result.innerHTML = search_phone + "的机主是:" + name;
- }
//查找数据 function find(){ var search_phone = document.getElementById("search_phone").value; var name = localStorage.getItem(search_phone); var find_result = document.getElementById("find_result"); find_result.innerHTML = search_phone + "的机主是:" + name; }
要展现所有已保存的联系人信息,则需要使用localStorage.key(index)方法,如下:
- //将所有存储在localStorage中的对象提取出来,并展现到界面上
- function loadAll(){
- var list = document.getElementById("list");
- if(localStorage.length>0){
- var result = "
";
";- result += "
姓名 手机号码 - for(var i=0;i
- var mobilephone = localStorage.key(i);
- var name = localStorage.getItem(mobilephone);
- result += "
"+name+" "+mobilephone+" - }
- result += "
- result += "
- list.innerHTML = result;
- }else{
- list.innerHTML = "目前数据为空,赶紧开始加入联系人吧";
- }
- }
//将所有存储在localStorage中的对象提取出来,并展现到界面上 function loadAll(){ var list = document.getElementById("list"); if(localStorage.length>0){ var result = "
姓名 | 手机号码 | "+name+" | "+mobilephone+" | "; } result += "
如下简单演示增加了公司属性的联系人保存JS代码:
- //保存数据
- function save(){
- var contact = new Object;
- contact.user_name = document.getElementById("user_name").value;
- contact.mobilephone = document.getElementById("mobilephone").value;
- contact.company = document.getElementById("company").value;
- var str = JSON.stringify(contact);
- localStorage.setItem(contact.mobilephone,str);
- loadAll();
- }
- //将所有存储在localStorage中的对象提取出来,并展现到界面上
- function loadAll(){
- var list = document.getElementById("list");
- if(localStorage.length>0){
- var result = "
";
";- result += "
姓名 手机 公司 - for(var i=0;i
- var mobilephone = localStorage.key(i);
- var str = localStorage.getItem(mobilephone);
- var contact = JSON.parse(str);
- result += "
"+contact.user_name+" "+contact.mobilephone+" "+contact.company+" - }
- result += "
- result += "
- list.innerHTML = result;
- }else{
- list.innerHTML = "目前数据为空,赶紧开始加入联系人吧";
- }
- }
//保存数据 function save(){ var contact = new Object; contact.user_name = document.getElementById("user_name").value; contact.mobilephone = document.getElementById("mobilephone").value; contact.company = document.getElementById("company").value; var str = JSON.stringify(contact); localStorage.setItem(contact.mobilephone,str); loadAll(); } //将所有存储在localStorage中的对象提取出来,并展现到界面上 function loadAll(){ var list = document.getElementById("list"); if(localStorage.length>0){ var result = "
姓名 | 手机 | 公司 | "+contact.user_name+" | "+contact.mobilephone+" | "+contact.company+" | "; } result += "

html5的div元素默认一行不可以放两个。div是一个块级元素,一个元素会独占一行,两个div默认无法在同一行显示;但可以通过给div元素添加“display:inline;”样式,将其转为行内元素,就可以实现多个div在同一行显示了。

html5中列表和表格的区别:1、表格主要是用于显示数据的,而列表主要是用于给数据进行布局;2、表格是使用table标签配合tr、td、th等标签进行定义的,列表是利用li标签配合ol、ul等标签进行定义的。

固定方法:1、使用header标签定义文档头部内容,并添加“position:fixed;top:0;”样式让其固定不动;2、使用footer标签定义尾部内容,并添加“position: fixed;bottom: 0;”样式让其固定不动。

HTML5中画布标签是“<canvas>”。canvas标签用于图形的绘制,它只是一个矩形的图形容器,绘制图形必须通过脚本(通常是JavaScript)来完成;开发者可利用多种js方法来在canvas中绘制路径、盒、圆、字符以及添加图像等。

html5中不支持的标签有:1、acronym,用于定义首字母缩写,可用abbr替代;2、basefont,可利用css样式替代;3、applet,可用object替代;4、dir,定义目录列表,可用ul替代;5、big,定义大号文本等等。

html5废弃了dir列表标签。dir标签被用来定义目录列表,一般和li标签配合使用,在dir标签对中通过li标签来设置列表项,语法“<dir><li>列表项值</li>...</dir>”。HTML5已经不支持dir,可使用ul标签取代。

html5是指超文本标记语言(HTML)的第五次重大修改,即第5代HTML。HTML5是Web中核心语言HTML的规范,用户使用任何手段进行网页浏览时看到的内容原本都是HTML格式的,在浏览器中通过一些技术处理将其转换成为了可识别的信息。HTML5由不同的技术构成,其在互联网中得到了非常广泛的应用,提供更多增强网络应用的标准机。

3种取消方法:1、给td元素添加“border:none”无边框样式即可,语法“td{border:none}”。2、给td元素添加“border:0”样式,语法“td{border:0;}”,将td边框的宽度设置为0即可。3、给td元素添加“border:transparent”样式,语法“td{border:transparent;}”,将td边框的颜色设置为透明即可。


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