JavaScript - Search pattern in string

Question

hello I would like to know what is the best way to search pattern like AB where A should be any except A and B should only be B ? Exempple : 'ADSDFSDAB' should return false where as 'BBBSDSSDSDNSSS' should return true.

So, for every B in my string, I want to return true if there is no A preceding it.

T.J. Crowder · Accepted Answer · 2016-12-18 11:35:15Z

2

where A should be any except A...

So that's [^A]

and B should only be B

And that's B.

So:

if (/[^A]B/.test(str))) {
    // Yes, it has a match
} else {
    // No, it doesn't
}

Live Example:

test("ADSDFSDAB", false);
test("BBBSDSSDSDNSSS", true);

function test(str, expect) {
  var result = /[^A]B/.test(str);
  var good = !result == !expect;
  console.log("'" + str + "': " + result + (good ? " - Pass" : " - FAIL"));
}

answered Dec 18, 2016 at 11:35

T.J. Crowder

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Comments

hjpotter92 · Accepted Answer · 2016-12-18 11:38:12Z

1

From what I understand, you want to match B not followed by A. You can use a patter like:

[^A]B

however, I'd suggest that you search for the existence of the substring AB in your original string and check the result.

originalString.indexOf('AB') !== -1

answered Dec 18, 2016 at 11:38

hjpotter92

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1 Comment

Casimir et Hippolyte Over a year ago

[^A]B doesn't match a B at the start of the string. Searching AB with indexOf is indeed the best way.

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