Run results for: startsWith vs indexOf vs lastIndexOf

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/15.2 Safari/605.1.15

Browser: Safari 15

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: 2 years ago

Test name	Executions per second
startsWith positive	2902679.2 Ops/sec
indexOf positive	2353333.0 Ops/sec
lastIndexOf positive	2905907.5 Ops/sec
startsWith negative	3463315.5 Ops/sec
indexOf negative	1478005.5 Ops/sec
lastIndexOf negative	2850240.5 Ops/sec
substring positive	2055061.1 Ops/sec
substring negative	2184654.0 Ops/sec

Script Preparation code:

hay = 'https://url.com/Lorem%20ipsum%20dolor%20sit%20amet,%20consectetur%20adipiscing%20elit.%20Aenean%20quis%20rhoncus%20odio.%20In%20nec%20congue%20tellus.%20Nunc%20pulvinar,%20urna%20et%20pretium%20malesuada,%20nisi%20massa%20imperdiet%20sem,%20vitae%20euismod%20nunc%20felis%20vestibulum%20quam.%20Suspendisse%20potenti.%20Quisque%20ut%20massa%20risus.%20Integer%20ac%20nisl%20vehicula%20quam%20tincidunt%20porttitor.%20Ut%20lacinia%20urna%20odio,%20eget%20tincidunt%20sem%20eleifend%20vel.%20Maecenas%20tincidunt,%20urna%20in%20sagittis%20ultrices,%20turpis%20nisi%20varius%20lectus,%20scelerisque%20egestas%20nibh%20velit%20sit%20amet%20diam.%20Pellentesque%20ac%20tellus%20tellus.%20Maecenas%20scelerisque%20maximus%20elit,%20non%20congue%20tortor%20elementum%20at.'
needle1 = 'https://url.com/Lorem%20ipsum%20dolor%20sit%20amet,%20consectetur%20adipiscing%20elit.%20Aenean%20quis%20rhoncus%20odio.%20In%20nec%20congue%20tellus.%20Nunc%20pulvinar,%20urna%20et%20pretium%20malesuada,%20nisi%20massa%20imperdiet%20sem,%20vitae%20euismod%20nunc%20felis%20vestibulum%20quam.%20Suspendisse%20potenti.%20Quisque%20ut%20massa%20risus.'
needle2 = 'https://url.com/Ut%20tincidunt%20pretium%20diam,%20quis%20tincidunt%20lacus%20elementum%20nec.%20Etiam%20sit%20amet%20hendrerit%20augue,%20sollicitudin%20blandit%20nunc.%20Quisque%20finibus%20tortor%20ante,%20sit%20amet%20mollis%20neque%20tempor%20ac.%20Integer%20vestibulum%20ultricies%20nibh,%20sed%20condimentum%20augue%20hendrerit%20vitae.'

console.assert(hay.startsWith(needle1))
console.assert(hay.indexOf(needle1) === 0)
console.assert(hay.lastIndexOf(needle1, 0) === 0)
console.assert(!hay.startsWith(needle2))
console.assert(!(hay.indexOf(needle2) === 0))
console.assert(!(hay.lastIndexOf(needle2, 0) === 0))
console.assert(hay.substring(0, needle1.length) === needle1)
console.assert(!(hay.substring(0, needle2.length) === needle2))

Tests:

startsWith positive
hay.startsWith(needle1)
indexOf positive
hay.indexOf(needle1) === 0
lastIndexOf positive
hay.lastIndexOf(needle1, 0) === 0
startsWith negative
hay.startsWith(needle2)
indexOf negative
hay.indexOf(needle2) === 0
lastIndexOf negative
hay.lastIndexOf(needle1, 0) === 0
substring positive
hay.substring(0, needle1.length) === needle1
substring negative
hay.substring(0, needle2.length) === needle2

Run results for: startsWith vs indexOf vs lastIndexOf

Compare substring matching performance.

startsWith positive

indexOf positive

lastIndexOf positive

startsWith negative

indexOf negative

lastIndexOf negative

substring positive

substring negative