Write a JavaScript program to sum the multiples of 3 and 5 under 1000.

Write a JavaScript program which accepts a number as input and inserts dashes (-) between each two even numbers.

Write a JavaScript program that accepts an array input from a user and finds the most frequent item in the array. Sample array : const arr1=[3, 'a', 'a', 'a', 2, 3, 'a', 3, 'a', 2, 4, 9, 3]; Sample Output : a ( 5 times )