d2/src/uid.js

Javascript library for DHIS2

/**
 * @module uid
 *
 * @description
 * Client side implementation of the DHIS2 code (uid) generator.
 * ({@link https://github.com/dhis2/dhis2-core/blob/ad2d5dea959aff3146d8fe5796cf0b75eb6ee5d8/dhis-2/dhis-api/src/main/java/org/hisp/dhis/common/CodeGenerator.java|CodeGenerator.java})
 *
 * This module is used to generate and validate DHIS2 uids. A valid DHIS2 uid is a 11 character string which starts with a letter from the ISO basic Latin alphabet.
 */

const abc = 'abcdefghijklmnopqrstuvwxyz'
const letters = abc.concat(abc.toUpperCase())

const ALLOWED_CHARS = `0123456789${letters}`

const NUMBER_OF_CODEPOINTS = ALLOWED_CHARS.length
const CODESIZE = 11

const CODE_PATTERN = /^[a-zA-Z]{1}[a-zA-Z0-9]{10}$/

function randomWithMax(max) {
    return Math.floor(Math.random() * max)
}

/**
 * Generate a valid DHIS2 uid. A valid DHIS2 uid is a 11 character string which starts with a letter from the ISO basic Latin alphabet.
 *
 * @return {string} A 11 character uid that always starts with a letter.
 *
 * @example
 * import { generateUid } from 'd2/lib/uid';
 *
 * generateUid();
 */
export function generateUid() {
    // First char should be a letter
    let randomChars = letters.charAt(randomWithMax(letters.length))

    for (let i = 1; i < CODESIZE; i += 1) {
        randomChars += ALLOWED_CHARS.charAt(randomWithMax(NUMBER_OF_CODEPOINTS))
    }

    // return new String( randomChars );
    return randomChars
}

/**
 * Tests whether the given code is valid.
 *
 * @param {string} code The code to validate.
 * @return {boolean} Returns true if the code is valid, false otherwise.
 *
 * @example
 * import { isValidUid } from 'd2/lib/uid';
 *
 * isValidUid('JkWynlWMjJR'); // true
 * isValidUid('0kWynlWMjJR'); // false (Uid can not start with a number)
 * isValidUid('AkWy$lWMjJR'); // false (Uid can only contain alphanumeric characters.
 */
export function isValidUid(code) {
    if (code == null) {
        return false
    }

    return CODE_PATTERN.test(code)
}