how to JavaScript check validate param LENGTH?

fhleung · 06-02-2015, 11:43 PM

If I have a HTML form that can input file, browse file
how to validate the file name LENGTH?

Code:

<script type="text/javascript">
function validate() {
var x = document.forms["myForm"]["photo"].value ;
var y = x.length ;
var extension = x.substr(y-3);
alert("begining... "+extension );

if ( x.match(/\./g) == null ) { alert("NO dot. type");  return false; }
if ( x.match(/\./g).length > 1 ) { alert("error");  return false; }

if ( x.match(/!/g)  != null ) { alert("symbol ! ");  return false; }
if ( x.match(/\@/g) != null ) { alert("symbol @ ");  return false; }
if ( x.match(/\#/g) != null ) { alert("symbol # ");  return false; }
if ( x.match(/\$/g) != null ) { alert("symbol $ ");  return false; }
if ( x.match(/\/g) != null ) { alert("symbol  ");  return false; }
if ( x.match(/\^/g) != null ) { alert("symbol ^ ");  return false; }
if ( x.match(/\&/g) != null ) { alert("symbol & ");  return false; }
if ( x.match(/\*/g) != null ) { alert("symbol * ");  return false; }
if ( x.match(/\(/g) != null ) { alert("symbol ( ");  return false; }
if ( x.match(/\)/g) != null ) { alert("symbol ) ");  return false; }
if ( x.match(/-/g) != null ) { alert("symbol - ");  return false; }

if ( y > 24 ) { alert("name too long " + y ); return false; }

if ( extension == "jpg" ) { alert("check 2 "+extension);
if ( x.match(/\./g).length == 1 ) { alert("symbol . ");  return true; }}
if ( extension == "png" ) { alert("check 2 "); 
if ( x.match(/\./g).length == 1 ) { alert("symbol . ");  return true; }}
if ( extension == "JPG" ) { alert("check 2 ");  return true; }
if ( extension == "PNG" ) { alert("check 2 ");  return true; }
if ( extension == "peg")  { alert("check 2 ");  return true; }

alert("finally...");
return false;
}
</script>
http://www.w3schools.com/jsref/tryit.asp?filename=tryjsref_fileupload_files
<form name="myForm" onsubmit="return validate();" action="upload.cgi" enctype="multipart/form-data" method="post">
<p><input name="photo" type="file" style="height:100px"/></p>
<p><input name="Submit" type="submit" value="Submit UPLOADING" style="width:400px; height:200px"/></p>&nbsp;</form>

I got onsubmit JavaScript validate() function
I also got SCRIPT.PHP.CGI.ASP at server side

COPY AND PASTE INTO YOUR .HTML file see if work =)

filename-length means filename like
filename.jpg = 12 char include extension
filename12.jpg = 14 char include extension

NevemTeve · 06-03-2015, 05:17 AM

What do you mean by validating the filename-length ?

AnanthaP · 06-03-2015, 06:24 AM

I suppose it would be something like this.name(length)

OK

NevemTeve · 06-03-2015, 07:26 AM

or this.name.length

dugan · 06-03-2015, 09:19 AM

I assume that part of what you want to do is block the file upload if the filename isn't valid? Here are some ideas on how to do that.

http://stackoverflow.com/q/4227043/240515

fhleung · 06-04-2015, 10:44 PM

OK ! so like following?

Code:

var x = document.forms["myForm"]["photo"].value ;
var y = x.length ;
var filter =  /^[a-zA-Z0-9]+\.(jpg|png|jpeg|PNG)$/  ;

I re-do the code line by line checking, the code work or not depends on old new IE, FF

fhleung · 06-09-2015, 09:11 PM

also, anyone know how to check validate file SIZE?

ANSWER: var z = document.getElementById("fs").files[0].size ;

Code:

var z = document.getElementById("fs").files[0].size   ;   
<input name="photo" id="fs" type="file" style="height:100px"/>

http://www.w3schools.com/jsref/tryit...leupload_files