Run results for: startswith vs indexOf vs regex

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:88.0) Gecko/20100101 Firefox/88.0

Browser: Firefox 88

Operating system: Windows

Device Platform: Desktop

Date tested: 3 years ago

Test name	Executions per second
lorem.startsWith("L");	24162766.0 Ops/sec
lorem.indexOf("L") === 0;	18868416.0 Ops/sec
LOREM_RE.test(lorem);	15653137.0 Ops/sec
lorem.startsWith("R");	24900338.0 Ops/sec
lorem.indexOf("R") === 0;	11927928.0 Ops/sec
ROLEM_RE.test(lorem);	18255120.0 Ops/sec
lorem && lorem[0] === "L";	204842400.0 Ops/sec

Script Preparation code:

 var lorem = "Lorem ipsum dolor sit amet, consectetur adipiscing elit. Praesent congue, ipsum non scelerisque convallis Lorem ipsum dolor sit amet, consectetur adipiscing elit. Praesent congue, ipsum non scelerisque convallis Lorem ipsum dolor sit amet, consectetur adipiscing elit. Praesent congue, ipsum non scelerisque convallis Lorem ipsum dolor sit amet, consectetur adipiscing elit. Praesent congue, ipsum non scelerisque convallis";
 var LOREM_RE = /^L/;
 var ROLEM_RE = /^R/;

Tests:

lorem.startsWith("L");
lorem.startsWith("L");
lorem.indexOf("L") === 0;
lorem.indexOf("L") === 0;
LOREM_RE.test(lorem);
LOREM_RE.test(lorem);
lorem.startsWith("R");
lorem.startsWith("R");
lorem.indexOf("R") === 0;
lorem.indexOf("R") === 0;
ROLEM_RE.test(lorem);
ROLEM_RE.test(lorem);
lorem && lorem[0] === "L";
lorem && lorem[0] === "L";

Run results for: startswith vs indexOf vs regex

lorem.startsWith("L");

lorem.indexOf("L") === 0;

LOREM_RE.test(lorem);

lorem.startsWith("R");

lorem.indexOf("R") === 0;

ROLEM_RE.test(lorem);

lorem && lorem[0] === "L";