Run results for: startsWith vs ===

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.0.0 Safari/537.36

Browser: Chrome 131

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: one year ago

Test name	Executions per second
a[i].startsWith(b[i]) when a[i] strictly equals b[i]	12.8 Ops/sec
a[i].startsWith(b[j]) when a[i] different than b[j]	142.3 Ops/sec
a[i] === b[i] when a[i] strictly equals b[i]	422.7 Ops/sec
a[i] === b[j] when a[i] different than b[j]	216.8 Ops/sec

Script Preparation code:

function get_data (){
const a = [ ], b = [ ] 
for(let i=0; i<1000; ++i)
  {
    const v = Math.random().toPrecision(50)
    a.push(v)
    b.push(v)
  }
  return [a, b]
}

Tests:

a[i].startsWith(b[i]) when a[i] strictly equals b[i]
{ const [a, b] = get_data() const pre = Date.now() let test = true for(let j=0; j<1000; ++j) for(let i=0; i<1000; ++i) test &= a[i].startsWith(b[i]) const post = Date.now() console.log(test === true, post - pre) }
a[i].startsWith(b[j]) when a[i] different than b[j]
{ const [a, b] = get_data() const pre = Date.now() let test = true for(let j=1; j<1000; ++j) for(let i=0; i<1000; ++i) test |= a[i].startsWith(b[j]) const post = Date.now() console.log(test === false, post - pre) }
a[i] === b[i] when a[i] strictly equals b[i]
{ const [a, b] = get_data() const pre = Date.now() let test = true for(let j=0; j<1000; ++j) for(let i=0; i<1000; ++i) test &= a[i] === b[i] const post = Date.now() console.log(test === true, post - pre) }
a[i] === b[j] when a[i] different than b[j]
{ const [a, b] = get_data() const pre = Date.now() let test = true for(let j=1; j<1000; ++j) for(let i=0; i<1000; ++i) test |= a[i] === b[j] const post = Date.now() console.log(test === false, post - pre) }

Run results for: startsWith vs ===

a[i].startsWith(b[i]) when a[i] strictly equals b[i]

a[i].startsWith(b[j]) when a[i] different than b[j]

a[i] === b[i] when a[i] strictly equals b[i]

a[i] === b[j] when a[i] different than b[j]