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Which values get shown by the "for" loop?

importance: 4

For each loop write down which values it is going to show. Then compare with the answer.

Both loops alert same values or not?

  1. The postfix form:

    for (let i = 0; i < 5; i++) alert( i );
  2. The prefix form:

    for (let i = 0; i < 5; ++i) alert( i );

The answer: from 0 to 4 in both cases.

for (let i = 0; i < 5; ++i) alert( i );

for (let i = 0; i < 5; i++) alert( i );

That can be easily deducted from the algorithm of for:

  1. Execute once i=0 before everything (begin).
  2. Check the condition i<5
  3. If true – execute the loop body alert(i), and then i++

The increment i++ is separated from the condition check (2). That’s just another statement.

The value returned by the increment is not used here, so there’s no difference between i++ and ++i.