如果陈述无效的JavaScript

Question

I need help with javascript. here is my problem:

<script type="text/javascript">
    function validateForm() {
        var ime = document.getElementById('ime');
        var prezime = document.getElementById('prezime');
        var telefon = document.getElementById('telefon');
        var datum = document.getElementById('datum');
        var patt1 = /^\+[0-9]+$/;
        if (telefon.match(patt1) == null) {
            alert("Niste dobro uneli broj");

        }
        if (ime.value.length == 0 && prezime.value.length == 0 && telefon.value.length == 0 && datum.value.length == 0) {
            alert("Niste dobro uneli podatke!");
            return false;
        }

    }
</script>
<form action="popup.php" method="post" onsubmit="return validateForm()">Vase ime:
    <input type="text" name="ime" id="ime"> <br/>
    Vase prezime:
    <input type="text" name="prezime" id="prezime"> <br/>
    Broj telefona:
    <input type="text" name="telefon" id="telefon"> <br/>
    Datum rodjenja:
    <input type="text" name="datum" id="datum"> <br/>
    <input type="submit" name="save" value="sacuvaj">
</form>

I don't understand why telefon.match(patt1)==null) doesn't work. Please help!

Answer 1

Reason is because you can't apply regex to HTML Element, you can apply it to its value:

var telefon = document.getElementById('telefon').value;

Then you can execute your regex on var telefon

Answer 2

telefon is a DOM element, not a string

telefon.value can be matched

Answer 3

The object stored in telefon will be a DOM element (eg HTMLDivElement ), which has no method "match". You'll want to extract the pertinent text from that element before matching. How you do that will depend on the exact DOM type:

if (telefon.value.match(patt1) == null) // For form elements...

if (telefon.innerHTML.match(patt1) == null) // For "plain" DOM elements...