38 lines
1019 B
JavaScript
38 lines
1019 B
JavaScript
|
var random = require('./random')
|
|||
|
|
var url = require('../url')
|
|||
|
|
|
|||
|
|
/**
|
|||
|
|
* Generate secure URL-friendly unique ID. Non-blocking version.
|
|||
|
|
*
|
|||
|
|
* By default, ID will have 21 symbols to have a collision probability similar
|
|||
|
|
* to UUID v4.
|
|||
|
|
*
|
|||
|
|
* @param {number} [size=21] The number of symbols in ID.
|
|||
|
|
*
|
|||
|
|
* @return {Promise} Promise with random string.
|
|||
|
|
*
|
|||
|
|
* @example
|
|||
|
|
* const nanoidAsync = require('nanoid/async')
|
|||
|
|
* nanoidAsync.then(id => {
|
|||
|
|
* model.id = id
|
|||
|
|
* })
|
|||
|
|
*
|
|||
|
|
* @name async
|
|||
|
|
* @function
|
|||
|
|
*/
|
|||
|
|
module.exports = function (size) {
|
|||
|
|
size = size || 21
|
|||
|
|
return random(size).then(function (bytes) {
|
|||
|
|
var id = ''
|
|||
|
|
// Compact alternative for `for (var i = 0; i < size; i++)`
|
|||
|
|
while (size--) {
|
|||
|
|
// We can’t use bytes bigger than the alphabet. 63 is 00111111 bitmask.
|
|||
|
|
// This mask reduces random byte 0-255 to 0-63 values.
|
|||
|
|
// There is no need in `|| ''` and `* 1.6` hacks in here,
|
|||
|
|
// because bitmask trim bytes exact to alphabet size.
|
|||
|
|
id += url[bytes[size] & 63]
|
|||
|
|
}
|
|||
|
|
return id
|
|||
|
|
})
|
|||
|
|
}
|