Image upload judgment and preview script effect examples_javascript skills

 
                                                                                                 -130px;cursor:pointer;"/>
var $$ = function(id) {
return "string" == typeof id ? document.getElementById(id) : id;
};
/*
Image verification
*/
//Verify uploaded image format
function checkupload(ele) {
var obj = $$("FileUploadImg");
var fileContentType = obj.value.match(/^(.*)(.)(.{1,8})$/)[3]; //This file type regular expression is very useful:) 
 if (fileContentType == 'gif' || fileContentType == 'jpeg' || fileContentType == 'png' || fileContentType == 'jpg') {
                                                                                                                                                     } else {
        alert('The format of the uploaded file is incorrect!'); function checkFileSize(ele) {
var maxSize = 100 * 1024;
//ie
if (window.navigator.userAgent.indexOf("MSIE") >= 1) {
var fso ;
try {
fso = new ActiveXObject('Scripting.FileSystemObject');
var file = fso.GetFile(ele.value);
//alert(file.Size);
                                                                                                   . }
//firefox
else if (window.navigator.userAgent.indexOf("Firefox") >= 1) {
//alert(ele.files[0].fileSize);
return ele.files[0].fileSize < maxSize;
}
return false;
}
//Load preview image
function previewImage(ele) {
if (ele && checkupload(ele)) {
var imgDiv = $$("imgbox");
imgDiv.innerHTML = "";
imgDiv.style.width = "100px";
imgDiv.style .height = “125px”; Microsoft.AlphaImageLoader(sizingMethod = scale)";
                                                                         window. navigator.userAgent.indexOf("Firefox") >= 1) {
      imgDiv.innerHTML = "";
        } else {
                 imgDiv.innerHTML = "IE/Firefox browser Only supports image preview ";
}
} else {
        $$("FileUploadImg").value = ""; "";
                                     //alert('Reset upload control' );
}
}