Roughing out the demo app

node_modules/nanoid/async/format.js

@@ -0,0 +1,56 @@
+/**
+ * Secure random string generator with custom alphabet.
+ *
+ * Alphabet must contain 256 symbols or less. Otherwise, the generator
+ * will not be secure.
+ *
+ * @param {asyncGenerator} random The random bytes generator.
+ * @param {string} alphabet Symbols to be used in new random string.
+ * @param {size} size The number of symbols in new random string.
+ *
+ * @return {Promise} Promise with random string.
+ *
+ * @example
+ * const formatAsync = require('nanoid/async/format')
+ *
+ * function random (size) {
+ *   const result = []
+ *   for (let i = 0; i < size; i++) {
+ *     result.push(randomByte())
+ *   }
+ *   return Promise.resolve(result)
+ * }
+ *
+ * formatAsync(random, "abcdef", 5).then(id => {
+ *   model.id = id //=> "fbaef"
+ * })
+ *
+ * @name formatAsync
+ * @function
+ */
+module.exports = function (random, alphabet, size) {
+  var mask = (2 << 31 - Math.clz32((alphabet.length - 1) | 1)) - 1
+  var step = Math.ceil(1.6 * mask * size / alphabet.length)
+  size = +size
+
+  function tick (id) {
+    return random(step).then(function (bytes) {
+      for (var i = step; i--;) {
+        var byte = bytes[i] & mask
+        if (alphabet[byte]) {
+          id += alphabet[byte]
+          if (id.length === size) return id
+        }
+      }
+      return tick(id)
+    })
+  }
+
+  return tick('')
+}
+
+/**
+ * @callback asyncGenerator
+ * @param {number} bytes The number of bytes to generate.
+ * @return {Promise} Promise with array of random bytes.
+ */