<div id="box" class="">

<p>asdhhasd</p>

<p>sadhuasi</p>

<p>sadhuasi</p>

<p>sadhuasi</p>

<p>sadhuasi</p>

<p id="para">ewresfsd</p>

<p>sadhuasi</p>

</div>

​function getBoy(node) {

var o = node;

while(o.previousSibling != null) {

if(o.previousSibling.nodeType == 1) {

return o.previousSinbling;

}

o = o.previousSibling;

}

return null;

}

console.log(getBoy(para));

function getElementPrevSibling(node) {

var o = node;

while(o.previousSibling != null) {

if(o.previousSibling.nodeType == 1) {

//找到后，循环结束

return o.previousSibling;

}

//让o成为它的前一个节点

o = o.previousSibling;

}

return null;

}

console.log(getElementPrevSibling(para));