Detailed explanation of the implementation principle and process code of Javascript rounded div

Nowadays, the rounded corners are generally controlled by pictures. This method has its advantages (the resulting rounded corners are smooth). But at the same time, he also requires matching pictures. If he wants to dynamically change the style and color of p, it will be a bit difficult. There is also the use of js to achieve.

The calling code after implementation is as follows

var objp = getRoundp.call(document,"solid 1px yellow","#dddddd") 
objp.p.style.width="100px"; 
objp.Content.style.margin="6 6 6 6 " 
objp.Content.innerText="这是一个圆角p测试" 
document.body.appendChild(objp.p);

This produces a rounded corner p
Implementation principle: The principle is actually very simple. Add three lines to top and bottom, and use the different lengths of these three lines to create a rounded corner effect.
Implementation process: How to implement these three lines. Use the element and set its height to 1px. If you want to display borders, add left and right borders to them. After adding the lines, put the content p and these three lines in a container, which is also a p. Finally, a p class is returned. This class contains two attributes. One is the container p. Through this container p, the position, size and height of the graphics can be controlled. Another attribute is the content p. Through this p, you can set the content, margin, font color, background color, font size, and other attributes of this p.
Note: Calling the getRoundp method requires passing a method context. My understanding is that the method context is equivalent to a pointer pointing to the object on which the method is called. Why use this method context? For example, if you want to create a new rounded p in the popup document generated by IE's creatPopup method, since the popup can only load controls created by itself, the popup object can be passed into the method and become the object pointed to by the method context. There are two methods of passing context function.call(obj,"arg1","arg2") similar to this. The other is function.apply(obj,arguments)
The detailed code is as follows:

/**************************************************************************/ 
/*Roundp.js 产生一个圆角p 
调用前需设置函数上下文(上下文是指，要创建p的窗口) 例如 var objp = getRoundp.call(document,"","#dddddd") 
函数参数argBorderStyle: 边框样式，字符串 例如 "1px solid black" 
函数参数argBgColor: 背景颜色，字符串 例如 "#ffffff" 
现在只支持边框为1像素 如果超过1像素产生的图形会比较奇怪 
如果不设置边框 则没有边框 可以正常使用 
本函数返回的是一个Roundp自定义类 
如果要设置p的内容请用 obj.Content.innerHtml 或 obj.Content.innerText设置 
如果要设置p的高度请用 obj.p.style.width obj.p.style.height设置 
*/ 
/**************************************************************************/ 
/**************************************************************************/ 
//取得一个圆角p 
function getRoundp(argBorderStyle,argBgColor){ 
    //创建元素 
    var pPane =this.createElement("p") 
    var pContent =this.createElement("p") 
    var pContentMax =this.createElement("p") 
    var bTop =this.createElement("b") 
    var bBottom =this.createElement("b") 
    var bTop1 =this.createElement("b") 
    var bTop2 =this.createElement("b") 
    var bTop3 =this.createElement("b") 
    var bTop4 =this.createElement("b") 
    var bBottom1 =this.createElement("b") 
    var bBottom2 =this.createElement("b") 
    var bBottom3 =this.createElement("b") 
    var bBottom4 =this.createElement("b") 
    //背景设置 
    pPane.style.backgroundColor=argBgColor; 
    pContent.style.backgroundColor=argBgColor; 
    pContentMax.style.backgroundColor=argBgColor; 
    bTop1.style.backgroundColor=argBgColor; 
    bTop2.style.backgroundColor=argBgColor; 
    bTop3.style.backgroundColor=argBgColor; 
    bTop4.style.backgroundColor=argBgColor; 
    bBottom1.style.backgroundColor=argBgColor; 
    bBottom2.style.backgroundColor=argBgColor; 
    bBottom3.style.backgroundColor=argBgColor; 
    bBottom4.style.backgroundColor=argBgColor; 
    bTop.style.backgroundColor="#ffffff"; 
    bBottom.style.backgroundColor="#ffffff"; 
    //样式设置 
    bTop.style.overflow="hidden"; 
    bBottom.style.overflow="hidden"; 
    bTop1.style.overflow="hidden"; 
    bTop2.style.overflow="hidden"; 
    bTop3.style.overflow="hidden"; 
    bTop4.style.overflow="hidden"; 
    bBottom1.style.overflow="hidden"; 
    bBottom2.style.overflow="hidden"; 
    bBottom3.style.overflow="hidden"; 
    bBottom4.style.overflow="hidden"; 
    bTop.style.display="block"; 
    bBottom.style.display="block"; 
    bTop1.style.display="block"; 
    bTop2.style.display="block"; 
    bTop3.style.display="block"; 
    bTop4.style.display="block"; 
    bBottom1.style.display="block"; 
    bBottom2.style.display="block"; 
    bBottom3.style.display="block"; 
    bBottom4.style.display="block"; 
     
    //高度设置 
    pContent.style.height="100%"; 
    pContentMax.style.height="100%"; 
    bTop1.style.height="1px"; 
    bTop2.style.height="1px"; 
    bTop3.style.height="1px"; 
    bTop4.style.height="2px"; 
    bBottom1.style.height="1px"; 
    bBottom2.style.height="1px"; 
    bBottom3.style.height="1px"; 
    bBottom4.style.height="2px"; 
     
    //边框设置 
    pContentMax.style.borderLeft=argBorderStyle 
    pContentMax.style.borderRight=argBorderStyle 
    bTop1.style.borderLeft=argBorderStyle; 
    bTop1.style.borderRight=argBorderStyle; 
    bTop1.style.borderTop=argBorderStyle; 
    bTop2.style.borderLeft=argBorderStyle; 
    bTop2.style.borderRight=argBorderStyle; 
    bTop3.style.borderLeft=argBorderStyle; 
    bTop3.style.borderRight=argBorderStyle; 
    bTop4.style.borderRight=argBorderStyle; 
    bTop4.style.borderLeft=argBorderStyle; 
    bBottom1.style.borderLeft=argBorderStyle; 
    bBottom1.style.borderRight=argBorderStyle; 
    bBottom1.style.borderTop=argBorderStyle; 
    bBottom2.style.borderLeft=argBorderStyle; 
    bBottom2.style.borderRight=argBorderStyle; 
    bBottom3.style.borderLeft=argBorderStyle; 
    bBottom3.style.borderRight=argBorderStyle; 
    bBottom4.style.borderLeft=argBorderStyle; 
    bBottom4.style.borderRight=argBorderStyle; 
     
    //空白间距设置 
    bTop1.style.margin="0 4px 0 4px" 
    bTop2.style.margin="0 3px 0 3px" 
    bTop3.style.margin="0 2px 0 2px" 
    bTop4.style.margin="0 1px 0 1px" 
    bBottom1.style.margin="0 4px 0 4px" 
    bBottom2.style.margin="0 3px 0 3px" 
    bBottom3.style.margin="0 2px 0 2px" 
    bBottom4.style.margin="0 1px 0 1px" 
    //控件拼装 
    bTop.appendChild(bTop1); 
    bTop.appendChild(bTop1); 
    bTop.appendChild(bTop2); 
    bTop.appendChild(bTop3); 
    bTop.appendChild(bTop4);     
    bBottom.appendChild(bBottom4); 
    bBottom.appendChild(bBottom3); 
    bBottom.appendChild(bBottom2); 
    bBottom.appendChild(bBottom1); 
    pContentMax.appendChild(pContent) 
    pPane.appendChild(bTop) 
    pPane.appendChild(pContentMax) 
    pPane.appendChild(bBottom) 
    var objRoundp = new Roundp(); 
    objRoundp.p=pPane; 
    objRoundp.Content=pContent; 
    return objRoundp; 
} 
/**************************************************************************/ 
/**************************************************************************/ 
//自定义类（用来装载p对应内容） 
function Roundp(){ 
    this.content=0;//p内容 
    this.p=0;//p容器 
} 
/**************************************************************************/

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