Javascript nested function is not worked

Question

I do not understand why the feature does not work , I passed into the method foreach.

 var methods = {
            foreach: function(f){
                for(var i = 0; i <= this.x; i++){
                    f(i);
                }
            }
        };
        function test(x) {
           var t = Object.create(methods);
           t.x = x;
           return t;
        };
        var t = test(10);
        console.log(t.x); //10
        t.foreach(console.log()); //Uncaught TypeError: undefined is not a function

Thx!

t.foreach(console.log); //Uncaught TypeError: Illegal invocation — user4069489
– user4069489, Commented Feb 5, 2015 at 11:53
Thank you all ! This wrong example I saw in a book by David Flanagan: Javascript Pocket reference 3rd (page number 136) I did not think that there may be errors. — user4069489
– user4069489, Commented Feb 5, 2015 at 12:04

Quentin · Accepted Answer · 2015-02-05 11:37:39Z

1

You are passing the return value of calling console.log(), which isn't a function.

You need to pass an actual function.

Since log only works in the context of console you can't just pass console.log but you could, for instance:

 t.foreach(function (logthis) { console.log(logthis); });

answered Feb 5, 2015 at 11:37

Quentin

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