Correctly handle zero-length ANSI string (#15)

Author: kevin940726

index.js

@@ -7,7 +7,13 @@ const stringLength = string => {
 		return 0;
 	}
 
-	return stripAnsi(string).match(charRegex()).length;
+	const strippedString = stripAnsi(string);
+
+	if (strippedString === '') {
+		return 0;
+	}
+
+	return strippedString.match(charRegex()).length;
 };
 
 module.exports = stringLength;

test.js

@@ -3,6 +3,7 @@ const stringLength = require('.');
 
 test('get the real length of a string', t => {
 	t.is(stringLength(''), 0);
+	t.is(stringLength('\u001B[1m\u001B[22m'), 0);
 	t.is(stringLength('𠀔'), 1);
 	t.is(stringLength('foo𠁐bar𠀃'), 8);
 	t.is(stringLength('あ'), 1);