Anagram of strings of arrays

This program is working for a single word but I want to pass an array of strings(more than one word).

let output = getAnagrams("CATCH"); //it is working for this

let output = getAnagrams(["catch", "Priest", "Monkey", "Bruise"]); 

I want it to work for this.

function swap(chars, i, j) {
    var tmp = chars[i];
    chars[i] = chars[j];
    chars[j] = tmp;
}
function getAnagrams(input) {
    let newInput = input.toString().toLowerCase();
    console.log(newInput);
    var counter = [],
        anagrams = [],
        chars = newInput.split(''),
        length = chars.length,
        i;

    for (i = 0; i < length; i++) {
        counter[i] = 0;
    }

    anagrams.push(newInput);
    i = 0;
    while (i < length) {
        if (counter[i] < i) {
            swap(chars, i % 2 === 1 ? counter[i] : 0, i);
            counter[i]++;
            i = 0;
            anagrams.push(chars.join(''));
        } else {
            counter[i] = 0;
            i++;
        }
    }
    // return anagrams;
}