实现：九九乘法表

//九九乘法表

function cEl(el){
  return document.createElement(el)
}
function jiujiu(){
  for(let i=1;i<=9;i++){
    let p = cEl('p');
    for(let j=1;j<=i;j++){
      let span = cEl('span');
      p.appendChild(span);
      span.className='spanCls';
      span.innerHTML = j+'*'+i+'='+i*j;
    }
    document.body.appendChild(p)
  }

}
jiujiu();

p{
  padding: 0;
  margin:0;
  border-left:1px solid;
}
.spanCls{
  width:100px;
  display:inline-block;
  border:1px solid;
  border-left:1px solid transparent;
  border-bottom:1px solid transparent;
  text-align: center;
}
p:last-child .spanCls{
  border-bottom:1px solid;
}