CODEWITHSUNDEEP
javascript
takteek
takteek

Reputation: 7110

Use Array.forEach to call an "instance" method

If I have an array of objects like:

function Fruit() {
    this.onTree = true;
}
Fruit.prototype.pick = function() {
    this.onTree = false;
};

var arr = [new Fruit(), new Fruit()];

Is there any way to use Array.forEach to call the pick method on each one without creating an extra anonymous function?

arr.forEach(function(f) { f.pick(); });

I thought maybe I could do something with Fruit.prototype.pick.call but then the this context of the call function is lost so I have to bind that and I end up with:

arr.forEach(Function.call.bind(Fruit.prototype.pick));

which works but it's pretty ugly. Basically I just want something like this from Java:

arr.forEach(Fruit::pick);

Upvotes: 1

Views: 232

Answers (3)

Phugo
Phugo

Reputation: 400

If you cannot use ES6 (but, well, it's 2017...) you can store your this reference

 var self = this;

function invoker(item){
    Item.pick.call(self);
}

 array.forEach(invoker)

Or just use a for loop

Upvotes: 0

Einsamer
Einsamer

Reputation: 1087

You missed () after Fruit definition, didn't you?

    function Fruit() {
        this.onTree = true;
    }
    Fruit.prototype.pick = function() {
        this.onTree = false;
    };

    var arr = [new Fruit(), new Fruit()];

    arr.forEach(function(val, index) {
        val.pick();
        console.log(val);
    })

I tested that one nd it change those fruit.onTree into false.

Upvotes: 1

Suren Srapyan
Suren Srapyan

Reputation: 68665

You can use many approaches, but at least you need to pass a function to forEach because that is it's syntax. But if you use ES6, you can work with arrow functions and it can be more beautiful.

arr.forEach(f => f.pick());

Upvotes: 5

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