function evensOnly (arrayNumbers) {
    arrayOdds = []
    for (i = 0; i < arrayNumbers.length; i++) {
        if (arrayNumbers[i]%2 == 0) {

        } else
            arrayOdds.push(arrayNumbers[i])
    }
    return arrayOdds;
}

console.log(evensOnly([2,3,5,13,14,21,99]))

var arrayAnimals = [
    {name : 'Cow', mammal : true},
    {name : 'Frog', mammal : false},
    {name : 'Lion', mammal : true},
    {name : 'Dog', mammal : true},
    {name : 'Chicken', mammal : false},
    {name : 'Human', mammal : true},
]
function mammalsOnly (arrayAnimals) {
    arraymammals = []
    for (i=0; i < arrayAnimals.length; i++) {
        if(arrayAnimals[i].mammal == true) {
            arraymammals.push(arrayAnimals[i].name)
        } else {

        }

    }
    return arraymammals;
}

console.log(mammalsOnly(arrayAnimals))