Run results for: wefiowjfoiewjfoiwef - MeasureThat.net

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_16_0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/84.0.4147.105 Safari/537.36

Browser: Chrome 84

Operating system: Mac OS X 10.16.0

Device Platform: Desktop

Date tested: 3 years ago

Test name	Executions per second
character index	3507038.0 Ops/sec
charAt()	3396389.0 Ops/sec
startsWith()	3402369.0 Ops/sec
slice()	2985061.0 Ops/sec
RegExp	2369608.0 Ops/sec

Website performance monitoring

Script Preparation code:

var str = '!foo bar baz';
var noop = Function.prototype;

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
const pattern = /^!/; if (pattern.test(str)) noop();