Single FORM INPUT causes submit on Enter/Return

This is a browser oddity that I’ve had to code around for years.  In most modern browsers (currently Mozilla Firefox 2.x and MSIE 7.0), when a FORM contains only one editable INPUT field pressing the Enter or Return key will automatically submit the form, but when there are more than one the form is not submitted.   This irregularity in the single field case is responsible for several odd errors, and often results in double-submits of form data to the server.

Here’s a newer solution to the problem, the ‘magic’ is in the javascript events that we’ve added to the FORM object itself, no longer do you have to place event handlers on every INPUT field as has often been done in the past.

NOTE: not completely valid XHTML for ease of documentation and readability.

<html>
<head>
<title>test of input submit</title>
<script type=”text/javascript”>
function keycheckForm(formObj,evt){
if(isEnter(evt)){
//alert(‘in form’);
if(checkFormInputs(formObj)){
formObj.submit();
}
}
}
/*
* Added to handle enter key press
* NOTE: this is based on  a ‘legacy’ function [checkEnter(e)] that returned the reverse boolean values.
* @param evt Event
* @return boolean
*/
function isEnter(evt){ //e is event object passed from function invocation
var characterCode; //literal character code will be stored in this variable
if(evt && evt.which){ //if which property of event object is supported (NN4)
characterCode = evt.which; //character code is contained in NN4’s which property
}else{
characterCode = evt.keyCode; //character code is contained in IE’s keyCode property
}
var rc = false;
if(characterCode == 13){ //if generated character code is equal to ascii 13 (if enter key)
rc = true;
}
return rc;
}
/**
* @param formObj Object
*/
function checkFormInputs(formObj){
var rc = false;
var allInputs=formObj.getElementsByTagName(‘INPUT’);
var formInputs = allInputs.length;
var textInputs=0;
if(formInputs>1){
var ct = allInputs.length;
var i;
for(i=0; i < ct; i++){
var inputObj = allInputs[i];
var typ = inputObj.type;
if ((typ==’text’) || (typ==’password’)) {
textInputs=textInputs+1;
}
}
if(textInputs>1){
rc=true;
}
}
if(rc==false){
//alert(“blocked because of size”);
}
return rc;
}
</script>
</head>
<body>
<form action=”example.php” method=”get” onkeypress=”return keycheckForm(this,event);” onsubmit=”return checkFormInputs(this);”>
<input type=”text” name=”textfield1″ value=”testing1″ />
<button type=”button” name=”mybutton” onclick=”this.form.submit();”>Click Me</button>
</form>
</body>
</html>

Cheers!

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