Dropdown field - first item should be blank - For more than one field (Sharepoint) - sharepoint

Question

I was looking for a solution to the problem of getting a blank default when using a lookup in a field in Sharepoint. Kit Menke's solution to "Dropdown field - first item should be blank" question works perfectly for my first field with a lookup. But I can't make it work if have more that one field in the same list where I need to insert a blank for each lookup field (works only for the first field). I tried adding a new "Web Part" and applying the same code to the second field, but doesn't work. Any ideas? Thanks in advance

Answer 1

Follow-up to my answer here: Dropdown field - first item should be blank
Version 2.0 allows you to add the names of your dropdowns to dropdownNames in the MyCustomExecuteFunction function. As with the first one, this will work only with required single select lookup fields. Also, in order to edit the page again and update your Content Editor Web Part you may have to choose a value for your dropdowns otherwise you get the dreaded An unexpected error has occurred.. Good luck! :D
<script type="text/javascript">
function GetDropdownByTitle(title) {
var dropdowns = document.getElementsByTagName('select');
for (var i = 0; i < dropdowns.length; i++) {
if (dropdowns[i].title === title) {
return dropdowns[i];
}
}
return null;
}
function GetOKButtons() {
var inputs = document.getElementsByTagName('input');
var len = inputs.length;
var okButtons = [];
for (var i = 0; i < len; i++) {
if (inputs[i].type && inputs[i].type.toLowerCase() === 'button' &&
inputs[i].id && inputs[i].id.indexOf('diidIOSaveItem') >= 0) {
okButtons.push(inputs[i]);
}
}
return okButtons;
}
function AddValueToDropdown(oDropdown, text, value, optionnumber){
var options = oDropdown.options;
var option = document.createElement('OPTION');
option.appendChild(document.createTextNode(text));
option.setAttribute('value',value);
if (typeof(optionnumber) == 'number' && options[optionnumber]) {
oDropdown.insertBefore(option,options[optionnumber]);
}
else {
oDropdown.appendChild(option);
}
oDropdown.options.selectedIndex = 0;
}
function WrapClickEvent(element, newFunction) {
var clickFunc = element.onclick;
element.onclick = function(event){
if (newFunction()) {
clickFunc();
}
};
}
function MyCustomExecuteFunction() {
// **** ADD YOUR REQUIRED SINGLE SELECT FIELDS HERE ***
var dropdownNames = [
'Large Lookup Field',
'My Dropdown Field'
];
var dropdownElements = [];
for (var d = 0; d < dropdownNames.length; d++) {
// find the dropdown
var dropdown = GetDropdownByTitle(dropdownNames[d]);
// comment this IF block out if you don't want an error displayed
// when the dropdown can't be found
if (null === dropdown) {
alert('Unable to get dropdown named ' + dropdownNames[d]);
continue;
}
AddValueToDropdown(dropdown, '', '', 0);
// collect all of our dropdowns
dropdownElements.push(dropdown);
}
// add a custom validate function to the page
var funcValidate = function() {
var isValid = true;
var message = "";
for (var d = 0; d < dropdownElements.length; d++) {
if (0 === dropdownElements[d].selectedIndex) {
// require a selection other than the first item (our blank value)
if (isValid) {
isValid = false;
} else {
message += "\n"; // already had one error so we need another line
}
message += "Please choose a value for " + dropdownNames[d] + ".";
}
}
if (!isValid) {
alert(message);
}
return isValid;
};
var okButtons = GetOKButtons();
for (var b = 0; b < okButtons.length; b++) {
WrapClickEvent(okButtons[b], funcValidate);
}
}
_spBodyOnLoadFunctionNames.push("MyCustomExecuteFunction");
</script>

Answer 2

How about prepending a null option to the select menu of sharepoint.Like,
$('#idOfSelectMenu').prepend('<option value="" selected>(None)</option>');
I used this approach and append this code only in the NewForm.aspx because in EditForm.aspx it will override the selected option.