Add is.emptyOrWhitespace() (#21)

index.js

@@ -183,11 +183,13 @@ const isAbsoluteMod2 = value => x => is.integer(x) && Math.abs(x % 2) === value;
 is.even = isAbsoluteMod2(0);
 is.odd = isAbsoluteMod2(1);
 
+const isWhiteSpaceString = x => is.string(x) && /\S/.test(x) === false;
 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);
+is.emptyOrWhitespace = x => is.empty(x) || isWhiteSpaceString(x);
 
 const predicateOnArray = (method, predicate, values) => {
 	// `values` is the calling function's "arguments object".

readme.md

@@ -182,6 +182,10 @@ Returns `true` if `value` is an odd integer.
 
 Returns `true` if `value` is falsy or an empty string, array, object, map, or set.
 
+##### .emptyOrWhitespace(value)
+
+Returns `true` if `is.empty(value)` or a string that is all whitespace.
+
 
 ##### .any(predicate, ...values)
 

test.js

@@ -468,6 +468,13 @@ test('is.empty', t => {
 	t.false(m.empty(tempSet));
 });
 
+test('is.emptyOrWhitespace', t => {
+	t.true(m.emptyOrWhitespace(''));
+	t.true(m.emptyOrWhitespace('  '));
+	t.false(m.emptyOrWhitespace('🦄'));
+	t.false(m.emptyOrWhitespace('unicorn'));
+});
+
 test('is.any', t => {
 	t.true(m.any(m.string, {}, true, '🦄'));
 	t.true(m.any(m.object, false, {}, 'unicorns'));