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Run results for:
char index vs charAt() vs slice() vs startsWith() vs RegExp --
Compare methods for testing string's beggining character.
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Embed Benchmark Result
<iframe src="https://measurethat.net/Embed?id=590449" width="100%" height="500px"></iframe>
Run details:
User agent:
Mozilla/5.0 (iPhone; CPU iPhone OS 18_3_1 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/18.3 Mobile/15E148 Safari/604.1
Browser:
Mobile Safari 18
Operating system:
iOS 18.3.1
Device Platform:
Mobile
Date tested:
one year ago
charAt()
142.4M/s
slice()
132.4M/s
character index
120.5M/s
RegExp
118.2M/s
startsWith()
59.4M/s
View exact numbers
Test name
Executions per second
✓
charAt()
142,382,960 Ops/sec
slice()
132,361,840 Ops/sec
character index
120,524,776 Ops/sec
RegExp
118,196,528 Ops/sec
startsWith()
59,412,852 Ops/sec
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();