Run results for: string based guid generation

Run details:

User agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Firefox/52.0

Browser: Firefox 52

Operating system: Linux

Device Platform: Other

Date tested: 7 years ago

Test name	Executions per second
undefined	1882734.2 Ops/sec
empty string	2069687.6 Ops/sec
random out of 1000	1411220.4 Ops/sec

Script Preparation code:

function generate_guid(s) {
    var i = 0,
        guid = '',
        n = s && s.length || 0;

    for (; i < 8; i++) {
        guid += (i < n) ? s[i] : '0';
    }

    guid += '-';

    for (i = 8; i < 12; i++) {
        guid += (i < n) ? s[i] : '0';
    }

    guid += '-';

    for (i = 12; i < 16; i++) {
        guid += (i < n) ? s[i] : '0';
    }

    guid += '-';

    for (i = 16; i < 20; i++) {
        guid += (i < n) ? s[i] : '0';
    }

    guid += '-';

    for (i = 20; i < 32; i++) {
        guid += (i < n) ? s[i] : '0';
    }

    return guid;
}

function randomString() {
    return Math.random().toFixed(16).slice(2);
}

function str32() {
    return randomString() + randomString();
}

var J = 0;
var repo = new Array(256).fill(0).map(str32);

Tests:

undefined
generate_guid()
empty string
generate_guid('')
random out of 1000
generate_guid(repo[J++ & 255])

Run results for: string based guid generation

convert string to guid

undefined

empty string

random out of 1000