Javascript Editor on Safari acts inconsistently

The javascript editor acts inconsistently on Safari. Sometimes it get s hung when it try to update/evaluate the code. Sometimes it will not type.

This seems to happen mostly when I have invalid/buggy code.

My Workout.

I went to and use one of there Try It Yourself buttons on the examples they give for every method/function. I cut out the action and then write my desired code and debug it. Then go back to Glise and past that in the editor. Since w3schools use web to display I just leave that out of the cut and paste.