Javascript regular expression unexpected results

Question

<form name="form1">
<input type="textbox" name="txtInput" />
<script type="text/javascript">
function validate() {
if (! document.form1.txtInput.value.match(/\bSun(il)? (Mishra)?\b/)){
    alert("Please enter valid value!");
} else {
    alert("Success!");
}
}
</script>
<input type="button" name="btnSubmit" onclick="validate()" value="Go" />

It gives success on Sunil Mishra, Sun Mishra but not for Sunil OR Sun. I tried entering the input with space, but that also doesn't work.

Is there some issue in the code?

remove the blank space

Rinku
– Rinku

2013-06-07 13:01:02 +00:00
Commented Jun 7, 2013 at 13:01 — Rinku
– Rinku, Commented Jun 7, 2013 at 13:01

Ry- · Accepted Answer · 2013-06-07 13:00:09Z

4

If the space is optional, it needs to be in the second group too:

/\bSun(il)?( Mishra)?\b/

The reason adding a space at the end won’t work is because there’s no word boundary (\b) at the end of a string after a space.

answered Jun 7, 2013 at 13:00

Ry-♦

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Comments

Spudley · Accepted Answer · 2013-06-07 13:01:00Z

1

/\bSun(il)? (Mishra)?\b/

The reason this doesn't match Sun or Sunil on its own without Mishra is because of the space between the two names in the regex pattern.

The space isn't shown as optional, so the pattern will fail to match if the space isn't present, even though Mishra is optional.

To fix this, move the brackets around Mishra to include the space before it:

/\bSun(il)?( Mishra)?\b/

answered Jun 7, 2013 at 13:01

Spudley

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1 Comment

Sunil Mishra Over a year ago

The pattern will not work even if space is added as pointed by minitech

Sly · Accepted Answer · 2013-06-07 13:10:35Z

0

Rather than having to add the space into the second group, as the other answers have pointed out, you can use: /\bSun(il)?\s*(Mishra)?\b/. This will allow more than one space, tabs, etc. while also keeping it out of the Mishra group's result.

answered Jun 7, 2013 at 13:10

Sly

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