javascript - Why is "forEach not a function" for this object?

Question

This is probably something really dumb, but I don't understand why this doesn't work.

var a = {"cat":"large"};

a.forEach(function(value, key, map){
    console.log(value);
});

Uncaught TypeError: a.forEach is not a function

http://jsfiddle.net/ty7z6pse/

Answer 1

Object does not have forEach, it belongs to Array prototype. If you want to iterate through each key-value pair in the object and take the values. You can do this:

Object.keys(a).forEach(function (key){
    console.log(a[key]);
});

Usage note: For an object v = {"cat":"large", "dog": "small", "bird": "tiny"};, Object.keys(v) gives you an array of the keys so you get ["cat","dog","bird"]