<meta charset="UTF-8"> <title>Title</title> <script> window.onload=function(){ var aUl=document.getElementById('ul1'); var oUl=document.getElementById('ul2'); var aLi=getElementsByClassName(oUl,'p','box'); alert(aLi.length); //console.log(aLi); function getElementsByClassName(parent,tagName,className){ var aEls=parent.getElementsByTagName(tagName); var arr=[]; for(var i=0;i<aEls.length;i++){ /*if(aEls[i].className=='box'){ arr.push(aEls[i]); }*/ var aClassName=aEls[i].className.split(' '); for(var j=0;j<aClassName.length;j++){ if(aClassName[j]==className){ arr.push(aEls[i]); } } } return arr; } } </script> </head> <body> <ul id="ul1"> <li class="box">11111</li> <li class="box1">11221</li> <li class="box box2">11311</li> <p class="box"> ppp</p> </ul> <ul id="ul2"> <li class="box">11111</li> <li class="box1">11221</li> <li class="box box2">11311</li> <p class="box"> ppp</p> </ul> </body> </html>
