27 lines
807 B
JavaScript
27 lines
807 B
JavaScript
'use strict'
|
|
|
|
var crypto = require('crypto')
|
|
|
|
var isInt = function (n) {
|
|
return Number(n) === n && n % 1 === 0
|
|
}
|
|
|
|
var isValid = function (input) {
|
|
var type = typeof input
|
|
if (type === 'number' && isNaN(input)) return false
|
|
return type === 'number' || type === 'string' || Buffer.isBuffer(input)
|
|
}
|
|
|
|
var toNumber = function (buf) {
|
|
return buf.readUInt16BE(0) * 0xffffffff + buf.readUInt32BE(2)
|
|
}
|
|
|
|
module.exports = function (input, max) {
|
|
if (max === undefined) max = Infinity
|
|
if ((!isInt(max) && max !== Infinity) || max <= 0) throw new Error('max must be positive integer')
|
|
if (!isValid(input)) throw new Error('Input must be a string, buffer or a number')
|
|
|
|
if (typeof input === 'number') input = input.toString()
|
|
return toNumber(crypto.createHash('sha1').update(input).digest()) % max
|
|
}
|