How do you know a girl likes you?

Okay so i have this friend who I've known since highschool and when we were seniors we got extremely close. Like, she would hit me and literally leave me bruises just cause. But she started messaging me about like going out for food and stuff. Then she would get jealous if I go out and not take her. Then she literally asked me out on a date and said yes. Like...is she just being funny or messing around?