SOURCE

const token = '6f8dfb0eb5814b059457ac1dbac125b1'
const reverseStr = token.split("").reverse().join("")
console.log(reverseStr)
const splitLength = 7

let result = ''
// 0-6 7-13 14-
for(var i =0; i< (reverseStr.length%splitLength) + 1; i++) {
    var index = i * splitLength
   result += reverseStr.substring(index, index + splitLength)
}

console.log(result)

console.log('2A4EC8B72590A7AC6289C7E032A218FB'.toLowerCase())

const str = '6f8dfb0eb5814b059457ac1dbac125b1'
console.log(12111,str.match('[0-9]+'))

// 1b521cabd1ca754950b4185be0bf