Fetch records from CloudKit's public database with vanilla Javascript.

FetchFromCloudKitPublicDB.js

const query = {
    "records": [
        {
            "recordName": "49A20D8A-A213-F2A4-71C3-E0758908F1D5"
        }
    ]
}

const container = 'iCloud.br.com.guilhermerambo.ChibiStudioModern'
const url = `https://api.apple-cloudkit.com/database/1/${container}/production/public/records/lookup`

fetch(url, {
    'method': 'POST',
    'headers': {'Content-Type': 'application/json'},
    'body': JSON.stringify(query)
}).then(response => {
    response.json().then(json => {
        console.log(json)
    })
}).catch(e => {
    console.error(e)
})