Program Won't Scan Properly The Text

I was trying to do a short program that scans a text for a given word and then tells you how many times that word was repeated in the text. The result was this:

var text = prompt("Write the text to be searched through");
var word = prompt("Write the word to be looked for. Beware of capitals!");
var hits = [];
for (var i = 0; i < text.length; i++) {
if (text[i] === word[0]) {

[Code] ....

However, this doesn't scan the text properly. I think the problem lies in one of the lines from 4 to 8, but, even after thinking quite a lot, I couldn't understand what was it. I thought that by saying that the letter of the text in position [i + k] shuold be equal to the letter of the word in position [k] I could make it work, but it doesn't.