From 46e886d10b3f4fdc4746c58f13e3c68285718651 Mon Sep 17 00:00:00 2001
From: Kodie Grantham <kodie.grantham@gmail.com>
Date: Fri, 6 Oct 2017 02:39:36 -0500
Subject: [PATCH] Add is.empty() (#16)

---
 index.js  |  6 ++++++
 readme.md |  5 +++++
 test.js   | 29 +++++++++++++++++++++++++++++
 3 files changed, 40 insertions(+)

diff --git a/index.js b/index.js
index f7a16fd..37f27f6 100644
--- a/index.js
+++ b/index.js
@@ -163,4 +163,10 @@ is.inRange = (x, range) => {
 
 is.infinite = x => x === Infinity || x === -Infinity;
 
+const isEmptyStringOrArray = x => (is.string(x) || is.array(x)) && x.length === 0;
+const isEmptyObject = x => !is.map(x) && !is.set(x) && is.object(x) && Object.keys(x).length === 0;
+const isEmptyMapOrSet = x => (is.map(x) || is.set(x)) && x.size === 0;
+
+is.empty = x => !x || isEmptyStringOrArray(x) || isEmptyObject(x) || isEmptyMapOrSet(x);
+
 module.exports = is;
diff --git a/readme.md b/readme.md
index fab01c1..8c9a29e 100644
--- a/readme.md
+++ b/readme.md
@@ -150,6 +150,11 @@ is.inRange(3, 10);
 Check if `value` is `Infinity` or `-Infinity`.
 
 
+##### .empty(value)
+
+Returns `true` if `value` is falsy or an empty string, array, object, map, or set.
+
+
 ## FAQ
 
 ### Why yet another type checking module?
diff --git a/test.js b/test.js
index a2c4337..336bc45 100644
--- a/test.js
+++ b/test.js
@@ -373,3 +373,32 @@ test('is.inRange', t => {
 test('is.infinite', t => {
 	testType(t, 'infinite', ['number']);
 });
+
+test('is.empty', t => {
+	t.true(m.empty(null));
+	t.true(m.empty(undefined));
+
+	t.true(m.empty(false));
+	t.false(m.empty(true));
+
+	t.true(m.empty(''));
+	t.false(m.empty('🦄'));
+
+	t.true(m.empty([]));
+	t.false(m.empty(['🦄']));
+
+	t.true(m.empty({}));
+	t.false(m.empty({unicorn: '🦄'}));
+
+	const tempMap = new Map();
+	t.true(m.empty(tempMap));
+
+	tempMap.set('unicorn', '🦄');
+	t.false(m.empty(tempMap));
+
+	const tempSet = new Set();
+	t.true(m.empty(tempSet));
+
+	tempSet.add(1);
+	t.false(m.empty(tempSet));
+});