how to remove all elements fron one array in another javascript code example

Example 1: js delete all from array

var list = [1, 2, 3, 4];
function empty() {
    //empty your array
    list.length = 0;
}
empty();

Example 2: remove all mutliple items from array javascript

arr = [2, 2, 2, 1, 3, 3, 3,3, 4, 5];
arr = arr.sort().filter((item,i)=>!(arr[i] == arr[i+1] || arr[i-1]==arr[i]));
// this will remove all item which are repeating more then one
console.log(arr);
// [1, 4, 5]