Frequency Counter / Multiple Pointers - areThereDuplicates(중복항목 확인)

Implement a function called, areThereDuplicates which accepts a variable number of arguments, and checks whether there are any duplicates among the arguments passed in.  You can solve this using the frequency counter pattern OR the multiple pointers pattern.

 

Examples:

1. areThereDuplicates(1, 2, 3) // false
2. areThereDuplicates(1, 2, 2) // true
3. areThereDuplicates('a', 'b', 'c', 'a') // true

function areThereDuplicates(...a) {
    let array_a =a.toString().split(',')
    let frequency_a = {};
    for (let val of array_a){
        frequency_a[val]=(frequency_a[val] || 0) +1
    }
    for (let key in frequency_a) {
        if (frequency_a[key]>1) return true;
    }return false;
}