Regular expression [^A-J] and match result

Question

Could you please explain, why output result of next match is s?

Update: I thought that output should be I as matched in regular range character.

var str = "Is this enough?";
var patt1 = new RegExp("[^A-J]");
var result = str.match(patt1); // ["s", index: 1, input: "Is this enought?"]
document.getElementById('id').innerHTML = result;

<p id="id"></p>

It would help if you could explain what you *expected* the result to be; as it is, nobody knows what it is that you think requires explanation. — Pointy, Dec 19 '15 at 16:08

Pointy · Accepted Answer · 2015-12-19T16:11:27.900

1

Your regular expression matches any character outside the range of upper-case A through upper-case J, and so s is the first character that meets that requirement. A regular expression like yours will match anywhere in the search string.

To be more clear, the ^ at the start of your character group expression means that the group should include all characters not described by the contents of the [^ ]. Your range is A-J, so [^A-J] matches all characters except A through J.

edited Dec 19 '15 at 16:11

answered Dec 19 '15 at 16:07

Pointy

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I'm a little bit confused about matching outside range – Maxim Zhukov Dec 19 '15 at 16:08
@FSou1 I don't understand what you mean. What did you expect the pattern to match? – Pointy Dec 19 '15 at 16:10
I have no idea why do you reply about 'matching any character outside the range'. Looks like that's because there is `^` – Maxim Zhukov Dec 19 '15 at 16:11
@FSou1 yes, that is exactly what that leading `^` means. If you want to match `A` through `J`, leave off the `^`. – Pointy Dec 19 '15 at 16:11

score 1 · Answer 2 · answered Dec 19 '15 at 16:07

1

^ means "match the char that is not in the set of the following characters". Because you haven't specified any flags, it returns only the first match. The first match is s, which is not in the set of characters A to J.

answered Dec 19 '15 at 16:07

nicael

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Doesn't `^` means to match any character in set at start of the string? – Maxim Zhukov Dec 19 '15 at 16:12
Not inside a character class it doesn't – PeeHaa Dec 19 '15 at 16:13
@FSou1 no - the `^` has two different roles in regular expressions. When it's at the start of a `[ ]` group, it means to match the complement of that group. You're thinking of `^` at the start of a pattern *outside* `[ ]`. – Pointy Dec 19 '15 at 16:13
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Looks like i confuse `/^A/` and `/[^A]/` – Maxim Zhukov Dec 19 '15 at 16:14

Regular expression [^A-J] and match result

2 Answers2