cannot read property 'forEach' of undefined

遍历数组报错：cannot read property ‘forEach’ of undefined
在遍历之前，判断数组是否存在

$scope.list=[];
//遍历之前，判断数组是否存在
if(!$scope.list){
	return;
}
$scope.list.forEach(function(item,i){
	console.log(item);
})