첨부파일 사이즈 확인 방법

Input FileUpload files Property

var x = document.getElementById("myFile");
var txt = "";
if ('files' in x) {
    if (x.files.length == 0) {
        txt = "Select one or more files.";
    } else {
        for (var i = 0; i < x.files.length; i++) {
            txt += (i+1) + ". file";
            var file = x.files[i];
            if ('name' in file) {
                txt += "name: " + file.name;
            }
            if ('size' in file) {
                txt += "size: " + file.size + " bytes";
            }
        }
    }
} 
document.getElementById ("demo").innerHTML = txt;

출처 : http://www.w3schools.com/jsref/prop_fileupload_files.asp