What is the difference between prefix and postfix operators?
JavaScript, Math · Oct 31, 2021

The increment operator (++
) adds 1
to its operand and returns a value. Similarly, the decrement operator (--
) subtracts 1
from its operand and returns a value. Both of these operators can be used either prefix (++i
, --i
) or postfix (i++
, i--
).
If used prefix, the value is incremented/decremented, and the value of the expression is the updated value.
let i = 0; // i = 0
let j = ++i; // i = 1, j = 1
let k = --i; // i = 0, k = 0
If used postfix, the value is incremented/decremented, and the value of the expression is the original value.
let i = 0; // i = 0
let j = i++; // i = 1, j = 0
let k = i--; // i = 0, k = 1
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