Passing scope to forEach

Question

I\'m trying to use a callback method addToCount instead of anonymous function in forEach. But I can\'t access this.count in it (return

Answer 1

Try something like this. I've used that rather than _this but also I've moved addToCount so it's inside countWords. That turns countWords into a closure containing that.

Words.prototype = {
  countWords: function() {
    var that = this, words = this.sentence.split(/\W+/);
    words.forEach(function(word) {
        word = word.toLowerCase();
        if (word == '') return;
        if (word in that.count)
          that.count[word] += 1;
        else
          that.count[word] = 1;
      });
  }
}

Answer 2

You need to use Function#bind to bind a scope:

words.forEach(this.addToCount.bind(this));

Note that this is not available in all browsers: you should use a shim (as provided in the link above) to add it in the browsers that don't support Function#bind.

---

As dandavis points out in the comments, you can pass a value to Array#forEach as the context for the callback:

words.forEach(this.addToCount, this);