Random

// with random
btoa(Math.random())

// with crypto
btoa(crypto.getRandomValues(new Uint8Array(16)))

// base64 has `=` remove them
btoa(Math.random()).replace(/=/g, "")

// lower case
btoa(Math.random()).toLowerCase()

// align length
btoa(Math.random()).substring(0, 10)

// letter only
btoa(crypto.getRandomValues(new Uint8Array(16))).replace(/[0-9]/g, "").replace(/=/g, "")

// number only
crypto.getRandomValues(new Uint8Array(16)).join("")