How to check the number of occurrences of one array in another?

Question

Arrays

Hello. Please help me to resolve the issue. I am a beginner, I just started learning JS, I googled, but I did not find how to solve just such a question.
There are two arrays

arr1 = [1,2,3,4,5,6,7,8,9]
arr2 = [3,4,5]

How to display the number of occurrences of elements of the second array in the first?
Thank you in advance.

Answer 1

Loop through the first array, and if the current character is equal to the first character from the second array, then start the comparison loop.
Exclusively for JS, there is a bad solution:
arr1.join().match(new RegExp(arr2.join(), "g")).length
Here each array is converted to a string and the number of occurrences is searched.