Javascript：数组中每个对象的调用方法，无需迭代

Question

Is there an elegant way of calling a method on each object in an array without iteration?

Edit: The intent of the question was to ask "without a for loop, or without any iteration if possible" Sorry for the confusion

var dogs = [new Dog("Max"), new Dog("Buddy"), new Dog("Charlie")];

for(var i=0; i<dogs.length; i++){
    dogs[i].sayName();
}

function Dog(name){

    this.name = name;

    this.sayName = function(){
         console.log(this.name);
    }

}

Answer 1

Use .forEach()

dogs.forEach(function(elem) {
   console.log(elem.sayName());
}

Alternatively you can use .map() , which returns a new array

dogs.map(function(elem) {
   return elem.name;
}

If you are using array.map() you should return something so you don't end up with a new array of undefined values, if you intend on using the returned array.

Using forEach() seems like a better fit in your use case.

However as @Barmar points out, both methods still iterate over each element in the array.

Answer 2

No

Doing something on each array item means you iterate the array.

So it's not possible to do it without iterating the array.

Answer 3

You could use forEach . Even the object initialisation could be done in a similar way with map :

 var dogs = ['Max','Buddy','Charly'].map(name => new Dog(name)); dogs.forEach(dog => dog.sayName()); function Dog(name){ this.name = name; this.sayName = function(){ console.log(this.name); } } 

Answer 4

You can use map :

dogs.map(function(thisDog) { thisDog.sayName(); })

The callback for map takes three arguments: the current value, the current index, and the array. But in your case you only need the current value so you don't need to provide the other two arguments.