用js实现预览待上传的本地图片_javascript技巧

<script> <BR>function preview5(){ <BR>var x = document.getElementById("file5"); <BR> if(!x || !x.value) return; <BR>var patn = /\.jpg$|\.jpeg$|\.gif$/i; <BR>if(patn.test(x.value)){ <BR>var y = document.getElementById("img5"); <BR>if(y){ <BR>y.src = "file://localhost/" + x.value; <BR>}else{ <BR>var img=document.createElement("img"); img.setAttribute("src","file://localhost/"+x.value); <BR>img.setAttribute("width","120"); <BR>img.setAttribute("height","90"); <BR>img.setAttribute("id","img5"); <BR>document.getElementById("form5").appendChild(img); <BR> } <BR>}else{ <BR>alert("您选择的似乎不是图像文件。"); <BR>}} <BR></script>