Using regex in javascript

Question

I cannot get to work the following example of Regex in JavaScript. Regex is valid, was tested on some webs testing Regex expression.

I want it to check if input is in format: xxx,xxx,xxx. It is alerting wrong input all the time. Thanks for any help.

        var re = /[0-9a-zA-Z]+(,[0-9a-zA-Z]+)*/; 
        var toValidation = document.getElementsByName("txtSerial").value;
        alert(toValidation);
        if(!re.test(toValidation))
            return true;
        else
        {
            alert("Please insert valid text.");
            return false;
        }

@anubhava the regex is incorrect too. It would match "123456". — Denys Séguret
– Denys Séguret, Commented Feb 5, 2014 at 12:51
Thanks dystroy ;) I didn't know about using /^ ... $/ what is it for? — user2775380
– user2775380, Commented Feb 5, 2014 at 12:52

UweB · Accepted Answer · 2014-02-06 09:06:18Z

2

document.getElementsByName("txtSerial") will return all elements by that name (node collection). Node collections do not have an attribute named value, thus, .value will be undefined (as can be seen by your alert).

Depending on your markup, you will want to use

document.getElementById("txtSerial")

or

document.getElementsByName("txtSerial")[0]

(although the last one is certainly not ideal).

edited Feb 6, 2014 at 9:06

answered Feb 5, 2014 at 12:51

UweB

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