Run results for: En-To-Em Dash Regex

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/118.0.0.0 Safari/537.36

Browser: Chrome 118

Operating system: Windows

Device Platform: Desktop

Date tested: one year ago

Option 5 (Normal)

1.0M/s

Option 6 (I Am Dumb)

1.0M/s

Option 2 (Lookaround)

954K/s

Option 1 (Lookarounds)

544K/s

Option 3 (Clever)

480K/s

Option 4 (Two-Pass)

410K/s

View exact numbers

Test name	Executions per second
✓ Option 5 (Normal)	1,038,175 Ops/sec
Option 6 (I Am Dumb)	1,031,174 Ops/sec
Option 2 (Lookaround)	954,240 Ops/sec
Option 1 (Lookarounds)	544,386 Ops/sec
Option 3 (Clever)	479,635 Ops/sec
Option 4 (Two-Pass)	409,656 Ops/sec

Script Preparation code:

const testString = "This – is – a –test –string – with – multiple – instances– of–the – pattern – and – some – variations – like–this –and this– ";
const regex1 = /(?<= )–(?= )|(?<! )– (?! )| –(?<! ) ?/g;
const regex2 = / (?=–)–? ?|– /g;
const regex3 = /(?<= )–(?! )|–(?= )|(?<! )– (?! )/g;
const regex4step1 = / +– +/g; // Remove cases with spaces on both sides
const regex4step2 = / +–|– +/g; // Remove extra spaces
const regex5 = / – | –|– /g;
const regex6 = / – ?|– /g;

Tests: