var string = "The quick brown fox jumps over the lazy dog";
var words = string.split(" ");
for (var i in words) {
console.log(typeof i) // "string"
console.log(i) // 0,1,2,3...n
}
I just found out that the type of i in the for loop is a string in this case. Why?
Property names are strings and the for (var i in words) loop you're using iterates the property names of the words object (which happens to include the array indexes). You should not be using for (var i in words) to iterate the elements of an array because it iterates properties, not only array elements.
You can use either of these forms to iterate the elements of an array:
for (var i = 0; i < words.length; i++) {
item = words[i];
}
Or, in modern browsers, you can use:
words.forEach(function(value, index) {
});
for (i in array) iterates all iterable properties of the array object, not only array elements. If your intention is to iterate only array elements, then you should not use for (i in array). Sometimes it works, but sometimes it is not so it is NOT advised or considered best practice. As to your MDN reference, read exactly what it says there. If properties have been added, it will iterate those too. It is NOT a good practice.
forloop.