在每个pre代码块中增加一个“复制代码”功能

1、给每一串代码元素增加复制代码节点JS代码

$(function(){
    let preList = $(".show pre");
    for (let pre of preList) {
        //给每个代码块增加上“复制代码”按钮
        let btn = $("复制代码");
        btn.prependTo(pre);
    }
});
 
/*执行复制代码操作*/
function preCopy(obj) {
    //执行复制
    let btn = $(obj);
    let pre = btn.parent();
    //为了实现复制功能。新增一个临时的textarea节点。使用他来复制内容
    let temp = $("<textarea></textarea>");
    //避免复制内容时把按钮文字也复制进去。先临时置空
    btn.text("");
    temp.text(pre.text() + '原文链接：' + window.location.href); //复制后戴上本站的链接
    temp.appendTo(pre);
    temp.select();
    document.execCommand("Copy");
    temp.remove();
    btn.text("复制成功");
    setTimeout(()=> {
        btn.text("复制代码");
    },1500);
}

2、CSS样式

.show pre {
    position: relative;
    font-family: Consolas,Monaco,"Andale Mono","Ubuntu Mono",monospace;
    word-wrap: normal;
    word-break: break-all;
    white-space: pre;
    overflow-x: scroll;
    overscroll-behavior-x: contain;
    margin-top: 10px;
    margin-bottom: 0;
    border-radius: 4px;
    z-index: 0;
    padding: 1em;
    line-height: 1.5;
    color: #ccc;
    background: #2d2d2d;
    font-size: 14px;
    padding-left: 50px;
}
.show pre .btn-pre-copy{
    -webkit-user-select: none;
    -moz-user-select: none;
    -ms-user-select: none;
    -khtml-user-select: none;
    user-select: none;
    position: absolute;
    top: 10px;
    right: 12px;
    font-size: 12px;
    line-height: 1;
    cursor: pointer;
    color: hsla(0,0%,54.9%,.8);
    transition: color .1s;
}
.show pre .btn-pre-copy:hover{
    color: #fff;
}

3、如何不想用插件，要显示pre的行数1,2,3,4,5

let preList = $(".show pre");
let ulList = []
for(let i=0; i<preList.length; i++){
  let ul = ''
  //给每个代码块增加上“复制代码”按钮
  let preNum = preList.eq(i).html().split(/\n/).length
  ul += '<ul>'
  for(let j=1; j<preNum; j++){
  	ul += '<li>' + (j) + '</li>'
  }
  ul += '</ul>'
  ulList.push(ul)
}
for(let i=0; i<preList.length; i++){
  for(let j=0; j<ulList.length; j++){
  	if(i == j){
  		preList.eq(i).append(ulList[j])
  	}
  }
}

4、CSS样式

.show pre ul{
    position: absolute;
    left: 0;
    top: 0;
    background: #464541;
    padding: 1em 10px;
    line-height: 1.5;
}