Question

items = 3;
$('#div').html(items + 1 + ' - ' + items + 3);

Trying to make #div display 4 - 6, but it instead shows 4 - 33. What am I missing?

Answer 1

As to why it happened:

first the parser reads items + 1, so fine and dandy, it’s 4

then it concatenates with ' - ', so now you have 4 -

then it sees + items, at this moment, you are dealing with String, so it concatenates with 3 (as items is 3), so you have 4 - 3

then you have another concatenation with 3, but the left operand is a string, so the right operand is type casted into String as well, so you have 4 - 33

To achieve what you want, you need to enclose the inner operations:

$('#div').html((items + 1) + ' - ' + (items + 3));