JS verification Upload File extension method collection

Instance 1

can only upload jpg image file instance

code is as follows

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<form action= "*.jsp" method= "POST" onsubmit= "return Check ()" > <input type= "file" name= "file" > <input Type= "Submit" value= "Upload" > </form> JS code Function Check2 () { var file = document. Getelementsbyname ("File"). Value; if (file== "") { Alert ("Please select File"); return false; } var strtemp = File.split ("."); var strcheck = strtemp[strtemp.length-1]; if (strcheck.touppercase () = = ' JPG ') { return true; }else { alert (' Upload file type is not correct! '); return false; } }

Verifying the extension of the uploaded file

The code is as follows

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<input type= "File" name= "file" id= "file" onchange= "Checkfilename (This)" > function Checkfilename (ID) { var Oktext =/txt|jpg|xml|zip/i;//Here is the allowed extension var filename = id.value;//Gets the value of the current File file field var newfilename = Filename.split ('. '); This is a point separating the file name, because the suffix must end with something. NewFileName = newfilename[newfilename.length-1];//This is getting file suffix, Because the split is an array, so the last array is the suffix name of the file. Newfilename.length is the current length,-1 is the position of the suffix, because it starts at 0. Start checking suffix if (Newfilename.search (oktext) = = 1) {//search If not just returned-1. This if the newfilename is not in Oktext, then the type that is not allowed to upload. var err=oktext.tostring ();//convert positive to character var errtext=err.replace (/^/|/+ (. *)/g, "");//End With regular substitution/start and/I var errtext=errtext.replace (/|/g, ","); Replace INTO, Alert ("Please upload as" +errtext+ ");/prompt Return } }

The above methods are very scalable, and I'll introduce you to a very strong display of code.

The code is as follows

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<script language= "JavaScript" > <!-- Go to left space function LTrim (s) { Return S.replace (/^s*/, ""); } Go to the right space function RTrim (s) { Return S.replace (/s*$/, ""); } Go to the left and right space function Trim (s) { return RTrim (LTrim (s)); } Get file name extension function Get_ext (F_path) { var ext = '; if (F_path!= null && trim (f_path). length > 0) { F_path = Trim (F_path); ext = f_path.substring (F_path.lastindexof (".") + 1, f_path.length); } return ext; } Verifying file name extension function Chk_ext (F_path) { var ext = get_ext (F_path); Customized according to requirements var accept_ext = new Array ("Doc", "PDF", "BPM", "JPEG", "JPG", "gif", "ppt", "xls"); var flag = false; if (ext!= ') { for (var i=0; i<accept_ext.length; i++) { if (ext = = Accept_ext[i]) Flag = true; } } return flag; } --> </SCRIPT>