feat: charset option for String.random

medikoo · Nov 29, 2019 · 2a20eeb · 2a20eeb
1 parent ceebe8d
commit 2a20eeb
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Showing 3 changed files with 33 additions and 6 deletions.
diff --git a/docs/string/random.md b/docs/string/random.md
@@ -21,3 +21,11 @@ _Note: When not applying this setting, accidental generation of same string is s
 ### `length: 10`
 
 Desired length of result string
+
+### `charset: null`
+
+Fixed list of possible characters
+
+```javascript
+random({ charset: "abc" }); // "bacbccbbac"
+```
diff --git a/string/random.js b/string/random.js
@@ -1,14 +1,24 @@
 "use strict";
 
 var isObject            = require("type/object/is")
-  , ensureNaturalNumber = require("type/natural-number/ensure");
+  , ensureNaturalNumber = require("type/natural-number/ensure")
+  , ensureString        = require("type/string/ensure");
 
 var generated = Object.create(null), random = Math.random, uniqTryLimit = 100;
 
 var getChunk = function () { return random().toString(36).slice(2); };
 
-var getString = function (length) {
-	var str = getChunk();
+var getString = function (length, charset) {
+	var str;
+	if (charset) {
+		var charsetLength = charset.length;
+		str = "";
+		for (var i = 0; i < length; ++i) {
+			str += charset.charAt(Math.floor(Math.random() * charsetLength));
+		}
+		return str;
+	}
+	str = getChunk();
 	if (length === null) return str;
 	while (str.length < length) str += getChunk();
 	return str.slice(0, length);
@@ -18,9 +28,10 @@ module.exports = function (/* options */) {
 	var options = arguments[0];
 	if (!isObject(options)) options = {};
 	var length = ensureNaturalNumber(options.length, { "default": 10 })
-	  , isUnique = options.isUnique;
+	  , isUnique = options.isUnique
+	  , charset = ensureString(options.charset, { isOptional: true });
 
-	var str = getString(length);
+	var str = getString(length, charset);
 	if (isUnique) {
 		var count = 0;
 		while (generated[str]) {

diff --git a/test/string/random.js b/test/string/random.js
@@ -8,7 +8,15 @@ var isValidFormat = RegExp.prototype.test.bind(/^[a-z0-9]+$/);
 describe("string/random", function () {
 	it("Should return string", function () { assert.equal(typeof random(), "string"); });
 	it("Should return by default string of length 10", function () {
-		assert.isAtLeast(random().length, 10);
+		assert.equal(random().length, 10);
+	});
+	it("Should support custom charset", function () {
+		var charset = "abc";
+		var result = random({ charset: charset });
+		assert.equal(result.length, 10);
+		for (var i = 0; i < result.length; ++i) {
+			assert.isAtLeast(charset.indexOf(result.charAt(i)), 0);
+		}
 	});
 	it("Should ensure unique string with `isUnique` option", function () {
 		assert.notEqual(random({ isUnique: true }), random({ isUnique: true }));