Is it possible to use a regex in Javascript's "getElementById" method?

J-blk

Hi All,

Apologies if this is a stupid question, I write all my code in Ruby but at the moment need to use some Greasemonkey scripts for a specific test and my Javascript is very, very limited... I've googled around, but can't find an exact answer... I essentially have a script that fills in various text fields, selects items from lists, etc on specific pages and that can be done easily with something like this:

document.getElementById("name").value = "1";

The problem is, the controls I am working with have names that vary to a certain degree on each execution or different pages. In my Ruby code, I can use regular expressions when identifying a control to work with but I don't see a way to do this with JS? I'd be looking to do something along these lines:

document.getElementById(/[\w\d]+/).value = "1";

Can something like that be done? How?

Thanks in advance.

stephenlane80

try this,

it loops through all the elements in FornName then checks if their names match the regex expression (not tested by the way)

var re = new RegExp(/[\w\d]+/);

for(i=0; i<document.FormName.elements.length; i++)
{
  var m = re.exec(document.FormName.elements[i].name);
  
  if (m != null) {
    //element name matches regex, so do something with element;
  }
}

ron_darrell

Or we could try doing what he asked for stephen

var re = new RegExp(/[\w\d]+/);
var m = re.exec(document.getElementById($whatever_id).value);
if (m != null) {
    //element name matches regex, so do something with element;
}

RD

stephenlane80

my way is better than your way !!

im a bit of a rookie with javascript !!

J-blk

Thanks, but none of these work for me... I'm sure I'm doing something wrong though. To make things clearer, let's take http://www.msn.com which has a text field with an id of "f1". So I could adapt your example Ron to be something like:

var re = new RegExp(/f1/);
var m = re.exec(document.getElementById($whatever_id).value);
if (m != null) {
alert(m);
}

Nothing is returned?

Bluefrog

Seems to be some confusion here between names and ids. You're looking to match to an id right? So...

var theForm = document.forms[0];
// declare our regex
var re = new RegExp(/[\w\d]+/);
// loop through the form elements
for(i = 0; i < theForm.elements.length; i++){
// execute our regular expression against each element id
var m = re.exec(theForm.elements[i].id);
if (m != null) {
    //element id matches regex, so do something with element id cause that's what we want to match
alert('We have a match on the form control with an id of ' + theForm.elements[i].id);
}
}

Ooooooooh, this is post 666 for me, the post of the beast!

J-blk

Thanks Bluefrog - but this doesn't seem to work for me either. I quickly tested it on www.msn.com, replacing the regex with f1, which is the id of the search text field on the page. Nothing is returned once again...

Bluefrog

Well, ran it myself on the msn page and debugged. Two issues - looking back at the documentation I think we should be using the test method rather than exec. Also, the f1 element you're looking for is in the second form on the page - document.forms[1]. Script below works - you could always amend it to loop through all the forms.

Should have double-checked this before I posted last time. Just stick the code below before the closing body tag.

<script type="text/javascript">
function checkRegs(){
var theForm = document.forms[1];
// declare our regex
var re = new RegExp(/f1/);
// loop through the form elements
for(i = 0; i < theForm.elements.length; i++){
// execute our regular expression against each element id
var m = re.test(theForm.elements[i].id);
if (m) {
    //element id matches regex, so do something with element id cause that's what we want to match
alert('We have a match on the form control with an id of ' + theForm.elements[i].id);
}
}
}

document.onLoad = checkReg();
</script>

J-blk

Thanks a lot Bluefrog, that does indeed work like I originally wanted . So I should be able to adapt it for the pages I'm working with. Thanks again!