const removeNonDuplicate = str => {
const arr = str.split("");
const duplicateArray = arr.filter(ch => {
return arr.indexOf(ch) !== arr.lastIndexOf(ch);
});
return duplicateArray.join("");
}
const str = "Bubble Occurrence Mammal xya";
console.log(removeNonDuplicate(str));
/*
run:
ubble ccurrece ammal a
*/