geese_filter.js

function gooseFilter(birds) {
    var geese = ["African", "Roman Tufted", "Toulouse", "Pilgrim", "Steinbacher"];

    // return an array containing all of the strings in the input array except those that match strings in geese
    return birds.filter((item) => geese.indexOf(item) < 0)
};

   
console.log(gooseFilter(["Mallard", "Hook Bill", "African", "Crested", "Pilgrim", "Toulouse", "Blue Swedish"]), ["Mallard", "Hook Bill", "Crested", "Blue Swedish"]);  
    
console.log(gooseFilter(["Mallard", "Barbary", "Hook Bill", "Blue Swedish", "Crested"]), ["Mallard", "Barbary", "Hook Bill", "Blue Swedish", "Crested"]);
    
console.log(gooseFilter(["African", "Roman Tufted", "Toulouse", "Pilgrim", "Steinbacher"]), []);