# What is the difference between prefix and postfix operators?

Angelos Chalaris · 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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