Add is.truthy() and is.falsy() (#25)

index.js

@@ -111,6 +111,9 @@ is.float64Array = isObjectOfType('Float64Array');
 is.arrayBuffer = isObjectOfType('ArrayBuffer');
 is.sharedArrayBuffer = isObjectOfType('SharedArrayBuffer');
 
+is.truthy = x => !!x; // eslint-disable-line no-implicit-coercion
+is.falsy = x => !x;
+
 is.nan = Number.isNaN;
 is.nullOrUndefined = x => is.null(x) || is.undefined(x);
 
@@ -188,7 +191,7 @@ const isEmptyStringOrArray = x => (is.string(x) || is.array(x)) && x.length ===
 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.empty = x => is.falsy(x) || isEmptyStringOrArray(x) || isEmptyObject(x) || isEmptyMapOrSet(x);
 is.emptyOrWhitespace = x => is.empty(x) || isWhiteSpaceString(x);
 
 const predicateOnArray = (method, predicate, values) => {

readme.md

@@ -121,6 +121,22 @@ is.asyncFunction(() => {});
 
 #### Miscellaneous
 
+##### .truthy(value)
+
+Returns `true` for all values that evaluate to true in a boolean context:
+
+```js
+is.truthy('🦄');
+//=> true
+
+is.truthy(undefined);
+//=> false
+```
+
+##### .falsy(value)
+
+Returns `true` if `value` is one of: `false`, `0`, `''`, `null`, `undefined`, `NaN`. 
+
 ##### .nan(value)
 ##### .nullOrUndefined(value)
 ##### .primitive(value)

test.js

@@ -289,6 +289,23 @@ test('is.dataView', t => {
 	testType(t, 'arrayBuffer');
 });
 
+test('is.truthy', t => {
+	t.true(m.truthy('unicorn'));
+	t.true(m.truthy('🦄'));
+	t.true(m.truthy(new Set()));
+	t.true(m.truthy(Symbol('🦄')));
+	t.true(m.truthy(true));
+});
+
+test('is.falsy', t => {
+	t.true(m.falsy(false));
+	t.true(m.falsy(0));
+	t.true(m.falsy(''));
+	t.true(m.falsy(null));
+	t.true(m.falsy(undefined));
+	t.true(m.falsy(NaN));
+});
+
 test('is.nan', t => {
 	testType(t, 'nan');
 });