Run results for: Subsequence by string manipulation or regex

Run details:

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/89.0.4389.90 Safari/537.36

Browser: Chrome 89

Operating system: Linux

Device Platform: Desktop

Date tested: 2 years ago

Test name	Executions per second
subsequence_re	512908.3 Ops/sec
subsequence	1936757.0 Ops/sec
subsequence_re (using already determined regexp)	1267451.0 Ops/sec

Script Preparation code:

var string = "Hello world";

function subsequence_re(str) {
  let final = []
  for(var i = 0; i < str.length; i += 1) {
    final[i] = "(" + str[i] + ")+";
  }
  return new RegExp(final.join("(.)*"));
}

function subsequence(a, b) {
  let index = 0
  for(let char of b) {
    if (a[index] === char) index += 1
  }
  return index == a.length
}

var regexp = subsequence_re("Hello")

Tests:

subsequence_re
subsequence_re("Hello").test(string);
subsequence
subsequence("Hello", string);
subsequence_re (using already determined regexp)
regexp.test(string);

Run results for: Subsequence by string manipulation or regex

subsequence_re

subsequence

subsequence_re (using already determined regexp)