[thelist] [JS] Truly checking for empty fields

Tom Dell'Aringa pixelmech at yahoo.com
Fri Apr 9 09:49:33 CDT 2004

Along the same lines - I've always wondered about this one. When you
require a field to not be empty, often you see validations do the

if(myField.value == ""){
  return false

This is fine for a tab or if the field is truly empty, but if I
simply enter a space I can bypass this validation. If you aren't then
validating the *type* of data afterwards, this can sneak through your

We have this function available which seems to work:

function requiredField(field) {
    var nonblanks = 0;
    var thisChar;
    for (i = 0; i < field.value.length; i++) {
        thisChar = field.value.charCodeAt(i);
        // 32 is a blank; 9 is a tab
        if (thisChar != 32 && thisChar != 9) 
            nonblanks += 1;
    if (nonblanks == 0) {
        return false;
    return true;

I'm not sure how reliable checking for the characer numbers 32 and 9
is. (Note: No need to support anything prior to NS6 or IE5). But it
seems to work. And again, I'm wondering if a regex is not a better
solution here.



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