Run results for: char index vs charAt() vs slice() vs startsWith() vs RegExp Fixed - MeasureThat.net

Run details:

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/111.0.0.0 Safari/537.36

Browser: Chrome 111

Operating system: Linux

Device Platform: Desktop

Date tested: one year ago

Test name	Executions per second
character index	9986010.0 Ops/sec
charAt()	9944444.0 Ops/sec
startsWith()	9912426.0 Ops/sec
slice()	9575970.0 Ops/sec
RegExp	5760889.0 Ops/sec
charCodeAt	6715545.0 Ops/sec
character index again	10095448.0 Ops/sec

Script Preparation code:

var str = '!foo bar baz';
var noop = Function.prototype;
var code = "!".charCodeAt(0)
var pattern = /^!/;

Tests:

character index
if (str[0] === '!') noop();
charAt()
if (str.charAt(0) === '!') noop();
startsWith()
if (str.startsWith('!')) noop();
slice()
if (str.slice(0, 1) === '!') noop();
RegExp
if (pattern.test(str)) noop();
charCodeAt
if(str.charCodeAt(0) === code) noop();
character index again
if (str[0] === '!') noop();