trim spaces and check for empty form elements

[Marjeta]

I'm trying to very that the user actually entered something in the form, and not just spaces.

I guess the problem is in the first line of isBlank() function. I've tried the following:

• elem.value.trim ();

• elem.value=elem .value.trim();

• elem.value=trim (elem.value);

• elem.value.repl ace(/^\s+|\s+$/g,"");

and none works. It correctly gives me an error message if I leave the field completely blank.But if there's anything in the field, it does not trim away the spaces.

I found the trim functions somewhere on the web, so I'm guessing they are probably fine.

Here's the code:

function check_myForm(){
    if(isBlank(myForm.ofc, 'Please enter ofc:')){
        return false;
    }
}
 
function isBlank(elem, helperMsg) {
    elem.value.replace(/^\s+|\s+$/g,"");
    if(elem.value.length == 0){
        alert(helperMsg);
        elem.focus();
        return true;
    }
    return false;
}
 
String.prototype.trim = function() {
    return this.replace(/^\s+|\s+$/g,"");
}
String.prototype.ltrim = function() {
    return this.replace(/^\s+/,"");
}
String.prototype.rtrim = function() {
    return this.replace(/\s+$/,"");
}function ltrim(str) { 
    for(var k = 0; k < str.length && isWhitespace(str.charAt(k)); k++);
    return str.substring(k, str.length);
}
function rtrim(str) {
    for(var j=str.length-1; j>=0 && isWhitespace(str.charAt(j)) ; j--) ;
    return str.substring(0,j+1);
}
function trim(str) {
    return ltrim(rtrim(str));
}
function isWhitespace(charToCheck) {
    var whitespaceChars = " \t\n\r\f";
    return (whitespaceChars.indexOf(charToCheck) != -1);
}

[acoder]

If you're trying to replace, you'd have to set the value of elem to the new value:

elem.value = elem.value.replace(...);

Alternatively, remove that line and just use the trim() method (that you've added to String):

if(elem.value.trim().length == 0){

[Marjeta]

Thanks for your response.

I tried your suggestion:

function isBlank(elem, helperMsg) {
    if(elem.value.trim().length == 0){
 

but it doesn't change the field.

Meanwhile I tried this one again, just for laughs:

function isBlank(elem, helperMsg) {
    elem.value=trim(elem.value);
    if(elem.value.length == 0){
    ...
 

and now it suddenly works exactly as I wanted it. Maybe I forgot a ; or something stupid like that when I first tried it.

But I'm still puzzled at why it doesn't work with string's member function.

[acoder]

If you want to change the value, then you would have to set elem.value as you've done. trim() will work if you use it on the value:

elem.value = elem.value.trim();

[Marjeta]

Yup, that works.

Didn't work 2-3 hours ago - before I had my coffee. I guess lack of caffeine caused me to do some typos, such as forgetting a semicolon.

By the way, this was me very first JavaScript. Yaaay, I can do JavaScript now!!! Need to add that to my resume :)

Thanks for your help!!!!

[acoder]

Well done! Since you're new to JavaScript, I would suggest you try going through some of the links in the Offsite Links sticky thread.