feat: array-like/ensure

README.md

@@ -297,6 +297,18 @@ isArrayLike("foo"); // false
 isArrayLike("foo", { allowString: true }); // true
 ```
 
+#### `array-like/ensure`
+
+If given argument is an array like, it is returned back. Otherwise `TypeError` is thrown.
+
+```javascript
+const ensureArrayLike = require("type/array-like/ensure");
+
+ensureArrayLike({ length: 0 }); // { length: 0 }
+ensureArrayLike("foo", { allowString: true }); // "foo"
+ensureArrayLike({}); // Thrown TypeError: null is not a regular expression object
+```
+
 ---
 
 #### Array length

array-like/ensure.js

@@ -0,0 +1,9 @@
+"use strict";
+
+var resolveException = require("../lib/resolve-exception")
+  , is               = require("./is");
+
+module.exports = function (value/*, options*/) {
+	if (is(value, arguments[1])) return value;
+	return resolveException(value, "%v is not an array like value", arguments[1]);
+};

test/array-like/ensure.js

@@ -0,0 +1,24 @@
+"use strict";
+
+var assert          = require("chai").assert
+  , ensureArrayLike = require("../../array-like/ensure");
+
+describe("array-like/ensure", function () {
+	it("Should return input value", function () {
+		var value = [];
+		assert.equal(ensureArrayLike(value), value);
+	});
+	it("Should allow strings with allowString option", function () {
+		var value = "foo";
+		assert.equal(ensureArrayLike(value, { allowString: true }), value);
+	});
+	it("Should crash on invalid value", function () {
+		try {
+			ensureArrayLike("foo");
+			throw new Error("Unexpected");
+		} catch (error) {
+			assert.equal(error.name, "TypeError");
+			assert(error.message.includes("is not an array like value"));
+		}
+	});
+});