Regex pattern to count a certain occurrences

Question

I am trying to match a word which have either space before it or after it or both .

var sample = " test-abc -test# @test _test hello-test@ test test "

Like in the above case the first 'test' will count as it has a space before it, the next will not count as it has no space, the third 'test' will count as it has a space after it ,similarly the fourth one too, the fifth one will not count as it has no spaces front or back and the last two will as they have spaces before and after.

function countOccurences(str,word){
       var regex = new RegExp("(\\b|(?<=_))"+word+"(\\b|(?<=_))","gi");
       console.log((str.match(regex)|| []).length);
    }

The function I have written count the exact word but do not consider the space so the output I get is 7 but what I am trying to get is 5.

Tim Biegeleisen · Accepted Answer · 2021-11-26 06:10:34Z

1

You may try using match() here:

var sample = " test-abc -test# @test _test hello-test@ test test ";
var matches = sample.match(/(?<=\s)test|test(?=\s)/g, sample);
console.log("There were " + matches.length + " matches of test with whitespace on one side");

The regex pattern used here says to match:

(?<=\s)test  test preceded by whitespace
|            OR
test(?=\s)   test followed by whitespace

Note that the 5 matches here were:

test-abc
@test
_test
test
test

edited Nov 26, 2021 at 6:10

answered Nov 26, 2021 at 6:04

Tim Biegeleisen

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7 Comments

souv21 Over a year ago

the last two which have whitespaces either side ,how to get those too.

Tim Biegeleisen Over a year ago

Sorry, I thought you wanted test only when it has exactly one whitespace on either side, not on both sides. I have updated my answer.

Tim Biegeleisen Over a year ago

I think you'll need double escaping if you want to use RegExp, so use: var regex = new RegExp("(?<=\\s)"+asset+"|"+asset+"(?=\\s)", "g");

Tim Biegeleisen Over a year ago

@souv21 Match on: /(?<=\s)test(?=[\W_])|(?<=[\W_])test(?=\s)/g

souv21 Over a year ago

thanks, its working the exact match now.

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