Javascript find index of word in string (not part of word)

I am currently using str.indexOf("word") to find a word in a string. But the problem is that it is also returning parts of other words.

Example: "I went to the foobar and ordered foo." I want the first index of the single word "foo", not not the foo within foobar.

I can not search for "foo " because sometimes it might be followed by a full-stop or comma (any non-alphanumeric character).