JavaScript: string.match regular expression help

Question

I have a javascript function that looks element id with certain patterns. So I have the following script:

if (f.elements[i].id.match(/DataList\[-\d{3}|\d{3}\]\.MemberId/)) {
  //do something
}

It should match elements with ids such as these:

DataList[-1].MemberId
DataList[-2].MemberId

And it does, however it also matches the following:

DataList[-1].FirstName
DataList[-2].FirstName

which I don't want.

Could any guru take a look at the regular expression above and point out what is going wrong?

Thanks,

Cullen

For the regex you posted to match the element names you listed, you'd need to change the \d{3} to \d{1,3}. See @Macarse's answer for a good explanation of what's going on. — Brendan Berg
– Brendan Berg, Commented Oct 26, 2009 at 17:26

Asaph · Accepted Answer · 2009-10-26 17:12:30Z

2

Try to anchor your regex at the beginning with a ^ and at the end with a $, group your digit match and allow 1-3 digits instead of just 3.

if (f.elements[i].id.match(/^DataList\[(-\d{1,3}|\d{1,3})\]\.MemberId$/)) {
  //do something
}

The way you had it, it was matching anything containing "DataList[-123" or containing "123].MemberId".

A simpler overall regex that accomplishes the same thing is:

if (f.elements[i].id.match(/^DataList\[-?\d{1,3}\]\.MemberId$/)) {
  //do something
}

answered Oct 26, 2009 at 17:01

Asaph

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Comments

Macarse · Accepted Answer · 2009-10-26 17:08:12Z

2

The or is saying:

DataList\[-\d{3} OR \d{3}\]\.MemberId/

This regex matches correctly:

DataList\[-?\d{1,3}\]\.MemberId

answered Oct 26, 2009 at 17:08

Macarse

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Cranium Slows · Accepted Answer · 2009-10-26 17:12:52Z

1

My suggestion

   if (f.elements[i].id.match(/DataList\[-[0-9]{1,3}\]\.MemberId/)) {
  }

The {} determines how many #s you want to support so 1-3 would match upu to [999]

answered Oct 26, 2009 at 17:12

Cranium Slows

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