[Fix] avoid calling Function until absolutely necessary

Fixes #41
inspect-js · May 6, 2021 · bce7ca6 · bce7ca6
1 parent 5f6cc2a
commit bce7ca6
Showing 1 changed file with 9 additions and 3 deletions.
diff --git a/index.js b/index.js
@@ -14,8 +14,7 @@ var getGeneratorFunc = function () { // eslint-disable-line consistent-return
 	} catch (e) {
 	}
 };
-var generatorFunc = getGeneratorFunc();
-var GeneratorFunction = getProto && generatorFunc ? getProto(generatorFunc) : false;
+var GeneratorFunction;
 
 module.exports = function isGeneratorFunction(fn) {
 	if (typeof fn !== 'function') {
@@ -28,5 +27,12 @@ module.exports = function isGeneratorFunction(fn) {
 		var str = toStr.call(fn);
 		return str === '[object GeneratorFunction]';
 	}
-	return getProto && getProto(fn) === GeneratorFunction;
+	if (!getProto) {
+		return false;
+	}
+	if (typeof GeneratorFunction === 'undefined') {
+		var generatorFunc = getGeneratorFunc();
+		GeneratorFunction = generatorFunc ? getProto(generatorFunc) : false;
+	}
+	return getProto(fn) === GeneratorFunction;
 };