


HTML5 has made many enhancements to Web Form, such as the new input type type, Form Validation, etc.
Placeholder is another new attribute added in HTML5. When this attribute is set in input or textarea, the content of the value will be displayed in the text box as a gray text prompt. When the text box gains focus, the prompt text disappear. In the past, this effect could only be achieved by using JavaScript. Firefox, Google Chrome, etc. expressed support for it, but IE was the only one that felt inconsistent!
For example:
Introducing a powerful attribute plug-in that allows IE to support placeholder. It is also compatible with other browsers that do not support placeholder. The code is as follows:
$(document).ready(function(){
var doc=document,
inputs=doc.getElementsByTagName('input'),
supportPlaceholder='placeholder'in doc.createElement('input'),
placeholder=function(input){
var text=input.getAttribute('placeholder'),
defaultValue=input.defaultValue;
if(defaultValue==''){
input.value=text
}
input.onfocus=function(){
if(input.value===text)
{
this.value=''
}
};
input.onblur =function(){
if(input.value====''){
this.value=text
}
}
};
if(!supportPlaceholder){
for(var i=0,len=inputs.length;i
text=input.getAttribute('placeholder');
if(input.type==='text'&&text){
placeholder(input)
}
}
}
});
Direct Copy the code and save it as a js file for reference. No need to do any processing, super convenient!
ex: This will indeed make IE's Input display the placeholder attribute, but if there is only one input on the page Fortunately, if there are multiple inputs, if the input does not fill in any value, then its empty input will automatically fill in the value of the placeholder, causing an error. For example:
The solution is to make your own judgment in the background. Maybe it can be solved in the above js file, and we will study it later~!

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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