jquery - Can I limit the length of an array in JavaScript?

Question

I want to display the product browsing history, so I am storing the product ids in a browser cookie.

Because the list of history is limited to 5 items, I convert the cookie value to an array, then check the length of it and cut the redundant.

The code below is what I have tried, but it does not work; the array item isn't removed.

I would like to ask how to limit the array length so it can only store 5 items?

Or

How can I cut the items after the array index 4?

var id = product_id;
var browseHistory = $.cookie('history');
if (browseHistory != null) {
  var old_cookie = $.cookie('history');
  var new_cookie = '';

  if (old_cookie.indexOf(',') != -1) {
    var arr = old_cookie.split(',');
    if (arr.length >= 5) {
      arr.splice(4, 1)
    }
  }

  new_cookie = id + ',' + old_cookie;
  $.cookie('history', new_cookie, { expires: 7, path: '/' });
} else {
  $.cookie('history', id, { expires: 7, path: '/' });
}

Answer 1

You're not using splice correctly:

arr.splice(4, 1)

this will remove 1 item at index 4. see here

I think you want to use slice:

arr.slice(0,5)

this will return elements in position 0 through 4.

This assumes all the rest of your code (cookies etc) works correctly