檢測上傳圖片的寬高，看是否符合你的要求

<script>
var img=null;
function s()
{
if(img)
img.removeNode(true);
img=document.createElement("img");
img.style.position="absolute";
img.style.visibility="hidden";
img.attachEvent("onreadystatechange",orsc);
img.attachEvent("onerror",oe);
document.body.insertAdjacentElement("beforeend",img);
img.src=inp.value;
}

function oe()
{
alert("cant load img");
}

function orsc()
{
if(img.readyState!="complete")return false;
alert("高:"+img.offsetHeight+"/n寬:"+img.offsetWidth);
}

</script>
<input type="file" Name="file" id="inp" value="默認值"><br>
<input οnclick="s()" type="button" value="點我一下給出要上傳圖片的大小及長、寬" name="button">