Run results for: .startsWith vs .charAt vs str[0] for single character

Run details:

User agent: Mozilla/5.0 (Linux; Android 10) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/99.0.4844.74 Mobile Safari/537.36

Browser: Chrome Mobile 99

Operating system: Android

Device Platform: Mobile

Date tested: 2 years ago

Test name	Executions per second
startsWith	1051.3 Ops/sec
.charAt	453.4 Ops/sec
str[0]	906.4 Ops/sec

HTML Preparation code:

<div></div>

Script Preparation code:

var data = window.data = [];
const possible = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
var TOTAL_STRINGS = window.TOTAL_STRINGS = 100000;

function getRandomInt(max) {
  return Math.floor(Math.random() * max);
}

function makeRandomString(len) {
  var text = "";
  for( var i=0; i < len; i++ ) {
    text += possible.charAt(getRandomInt(possible.length));
  }
  return text;
}

while (data.length < TOTAL_STRINGS) {
  data.push(makeRandomString(getRandomInt(20)));
}

Tests:

startsWith
var x = 0; var TOTAL_STRINGS = window.TOTAL_STRINGS; var data = window.data; var regex = window.regex; while (x < TOTAL_STRINGS) { const str = data[x]; str.startsWith("A"); x += 1; }
.charAt
var x = 0; var TOTAL_STRINGS = window.TOTAL_STRINGS; var data = window.data; var match = window.match; while (x < TOTAL_STRINGS) { const str = data[x]; str.charAt(0) === 'A'; x += 1; }
str[0]
var x = 0; var TOTAL_STRINGS = window.TOTAL_STRINGS; var data = window.data; var match = window.match; while (x < TOTAL_STRINGS) { const str = data[x]; str[0] === 'A'; x += 1; }

Run results for: .startsWith vs .charAt vs str[0] for single character

Testing some things

startsWith

.charAt

str[0]