1var toString = require('./toString');
2
3/** Used to generate unique IDs. */
4var idCounter = 0;
5
6/**
7 * Generates a unique ID. If `prefix` is given, the ID is appended to it.
8 *
9 * @static
10 * @since 0.1.0
11 * @memberOf _
12 * @category Util
13 * @param {string} [prefix=''] The value to prefix the ID with.
14 * @returns {string} Returns the unique ID.
15 * @example
16 *
17 * _.uniqueId('contact_');
18 * // => 'contact_104'
19 *
20 * _.uniqueId();
21 * // => '105'
22 */
23function uniqueId(prefix) {
24  var id = ++idCounter;
25  return toString(prefix) + id;
26}
27
28module.exports = uniqueId;
29