Emotions can be intense issues for those on the spectrum. Just because we don't always show emotions doesn't mean we don't have to cope with them. High stress emotions are the hardest, especially if dealing with breaks in routine or unexpected events.
Frustrations need early coaching and support work. Learning how to stop and take a few deep breaths and think about our next actions can be a challenge.
For example, a child is playing with toys but time for the school bus is coming up in fifteen minutes. Even forewarning can trigger a negative response. When that happens with my son, what ever he throws a fit over gets put away immediately. With some things, if he's cooperative, it can stay out until he gets home from school. He knows this and most days it works well with him.
Mostly the trigger is that change in events and interruption to what he's currently doing. It means switching tracks and that takes daily practice. I have been known to interrupt what he's doing in checking on him, just to give him that practice. It's going to happen a lot in life, especially at school or later in life in jobs and social interaction.
Recognizing when an emotion is overpowering is important too. It's okay to take a break and remove yourself from a situation when feeling overwhelmed. I employ this practice with my son as well. Signs that he is overwhelmed and needs a break are things like swinging his fist, hitting furniture, throwing a toy, shrieking, or clawing/biting himself.
I discuss with him that when he feels the impulse to do these things is when to take a break or stop and take a few deep breaths before doing anything else. He knows that it's not okay to hurt himself and that throwing things or swinging his fist could hurt someone else. Even so, this takes lots and lots of practice. There is no fast fix for these feelings or behaviors. Even with medications, my son still needs this practice. It is the coming years and crucial areas of school like Jr High, that I hope for this practice to pay off. Other support areas will be less for him at that time. So it's important to have behavioral practices in now.