用Object字面量来代替swtich／if...else

if (animal === ‘dog‘) {
  // TO DO ‘dog‘
} else if (animal === ‘cat‘) {
  // TO DO ‘cat‘  
} else if (animal === ‘bird‘) {
  // TO DO ‘bird‘  
} else if (animal === ‘fish‘) {
  // TO DO ‘fish‘  
} else {
   // TO DO ‘other‘  
}

swtich (animal) {
    case ‘dog‘:
        // TO DO ‘dog‘
        break;
    case ‘cat‘:
        // TO DO ‘cat‘  
        break;
    case ‘bird‘:
        // TO DO ‘bird‘ 
        break;
    case ‘fish‘:
        // TO DO ‘fish‘
        break;
     default:
        // TO DO ‘other‘
}

function getAnimalName(name) {
    var animals = {
        ‘dog‘: function () {
            return ‘dog‘;
        },
        ‘cat‘: function() {
            return ‘cat‘;
        },
        ‘bird‘: function() {
            return ‘bird‘;
        },
        ‘fish‘: function() {
            return ‘fish‘;
        },
        ‘default‘: function() {
            return ‘other‘;
        }
    };
    return (animals.name || animals.default)();
}
var animal = getAnimalName(‘dog‘);
console.log(animal);// ‘dog‘