Run results for: prefix check

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/62.0.3202.89 Safari/537.36

Browser: Chrome 62

Operating system: Windows

Device Platform: Other

Date tested: 7 years ago

Test name	Executions per second
startsWith	2662030.5 Ops/sec
cached RegExp	1704987.6 Ops/sec
uncached RegExp	2640831.5 Ops/sec
prefixMap	1703394.0 Ops/sec
for function	2051110.6 Ops/sec

Script Preparation code:

var prefixMap = new Map([['!', new RegExp('^!')]]);
var prefix = new RegExp('^!');
var message1 = '!test';
var message2 = 'test';

function startsWithPrefix (prefix, content) {
    for (let i = 0; i < prefix.length; i++)
        if (prefix[i] !== content[i]) return false;
    return true;
};

Tests:

startsWith
message1.startsWith('!'); message2.startsWith('!');
cached RegExp
prefix.test(message1); prefix.test(message2);
uncached RegExp
/^!/.test(message1); /^!/.test(message2);
prefixMap
prefixMap.get('!').test(message1); prefixMap.get('!').test(message2);
for function
startsWithPrefix('!', message1); startsWithPrefix('!', message2);

Run results for: prefix check

startsWith

cached RegExp

uncached RegExp

prefixMap

for function