Required field(s) validation v1.10- By NavSurf

Súper recomendado! hace un muy buen paro!

<pre><script language="JavaScript">
<!--

/***********************************************
* Required field(s) validation v1.10- By NavSurf
* Visit Nav Surf at http://navsurf.com
* Visit http://www.dynamicdrive.com/ for full source code
***********************************************/

function formCheck(formobj){
 // Enter name of mandatory fields
 var fieldRequired = Array("FirstName", "LastName");
 // Enter field description to appear in the dialog box
 var fieldDescription = Array("First Name", "Last Name");
 // dialog message
 var alertMsg = "Please complete the following fields:\n";

 var l_Msg = alertMsg.length;

 for (var i = 0; i < fieldRequired.length; i++){
  var obj = formobj.elements[fieldRequired[i]];
  if (obj){
   switch(obj.type){
   case "select-one":
    if (obj.selectedIndex == -1 || obj.options[obj.selectedIndex].text == ""){
     alertMsg += " - " + fieldDescription[i] + "\n";
    }
    break;
   case "select-multiple":
    if (obj.selectedIndex == -1){
     alertMsg += " - " + fieldDescription[i] + "\n";
    }
    break;
   case "text":
   case "textarea":
    if (obj.value == "" || obj.value == null){
     alertMsg += " - " + fieldDescription[i] + "\n";
    }
    break;
   default:
   }
   if (obj.type == undefined){
    var blnchecked = false;
    for (var j = 0; j < obj.length; j++){
     if (obj[j].checked){
      blnchecked = true;
     }
    }
    if (!blnchecked){
     alertMsg += " - " + fieldDescription[i] + "\n";
    }
   }
  }
 }

 if (alertMsg.length == l_Msg){
  return true;
 }else{
  alert(alertMsg);
  return false;
 }
}
// -->
</script>



&lt;!--SAMPLE FORM --------------------------------&gt;

<form name="formcheck" onsubmit="return formCheck(this);">
First Name: <input name="FirstName" size="25" type="text" />
Last Name: <input name="LastName" size="25" type="text" />
<input type="submit" value="Submit Form" />
</form>
</pre>

Limit file uploads by extension

Nice & easy! A great JS Script... I'm keeping the credits, this ain't mine!

<SCRIPT LANGUAGE="JavaScript">
<!-- Original:  ArjoGod, Shauna Merritt -->
<!-- Modified By:  Ronnie T. Moore, Editor -->

<!-- This script and many more are available free online at -->
<!-- The JavaScript Source!! http://javascript.internet.com -->

<!-- Begin
extArray = new Array(".jpg");
function LimitAttach(form, file) {
allowSubmit = false;
if (!file) return;
while (file.indexOf("\\") != -1)
file = file.slice(file.indexOf("\\") + 1);
ext = file.slice(file.indexOf(".")).toLowerCase();
for (var i = 0; i < extArray.length; i++) {
if (extArray[i] == ext) { allowSubmit = true; break; }
}
if (allowSubmit) form.submit();
else
alert("Please only upload files that end in types:  "
+ (extArray.join("  ")) + "\nPlease select a new "
+ "file to upload and submit again.");
}
//  End -->
</script>

And to make it work, just apply it on the submit input

<input type="submit" onclick="LimitAttach(this.form, this.form.input_file_name.value)" />