javascript - 'Length' Property Undefined while iterating Array

Question

Iterating an array to find the longest string. Each time I've received the error Cannot read property length of undefined. Console.log tells me that the length of the array as well as the length of the string are being read and understood so I cannot understand where there is an undefined property. In fact, I've just about tripled the original length of the program trying to make sure every variable is defined but still no good. Any help would be greatly appreciated.

function findLongestWord(str) {
  var longest = 0;
  var array = str.split(" ");
  var arrayL = array.length;
  for (i=0; i<=arrayL; i++) {
    var currentWord = array[i];
    var currentL = currentWord.length;
    if (currentL > longest) {
      currentL = longest;
    };
  };
  return longest;
};

findLongestWord("The quick brown fox jumped over the lazy dog");

Edit: While the below answers did solve the issue, I also just wanted to mention for people that may later google this thread that I also had to swap my final if statement from currentL = longest; to longest = currentL since longest is what I was ultimately returning.

Answer 1

The problem is the bounds of your iteration

for (i=0; i<=arrayL; i++) {

Note that you are going to be looking for array[array.length] doing this and that will always be undefined because the 10th item in an array of 10 items is [9], [10] is undefined.

Also, please use var here

for (var i=0; i < arrayL; i++) {