Simple ID generator

id-generate.js

"use strict"

// Creates a `generate` function using an alphabet, for optimally small IDs
// if you can only use certain characters. This could be useful for file name
// generators, minifiers, among many others. You *do* need to expand letter
// ranges, though.
module.exports = alphabet => {
    const charTable = [...new Set(Array.from(alphabet, x => `${x}`))]
    let counter = 0
    if (charTable.length < 2) {
        throw new TypeError("alphabet must have at least two distinct values")
    }

    return () => {
        let id = counter++
        const name = []
        while (id >= charTable.length) {
            name.push(charTable[id % charTable.length])
            id = id / charTable.length | 0
        }
        return name.reverse().join("")
    }
}