js验证上传图片大小和格式

function validatePicture(obj){ var boolResult = true; var imgUrlLength = obj.value.length; if(imgUrlLength != 0) { var imgUrl = obj.value.toLowerCase(); var imgUrlType = imgUrl.substring(imgUrlLength-4,imgUrlLength); if(imgUrlType != ".jpg" && imgUrlType != ".gif") { alert("上传文件格式不正确！"); obj.outerHTML = obj.outerHTML; boolResult = false; } else { var myImg = new Image(); myImg.src = obj.value; myImg.onreadystatechange = function () { if(myImg.readyState == "complete") { var fs = myImg.fileSize; if(fs > 1024*50) //50KB { alert("上传图片不能超过50KB！"); obj.outerHTML = obj.outerHTML; boolResult = false; } } } } } return boolResult; }使用时直接 onchange validatePicture(this)就可以了