if...else

The if statement executes a statement if the last item on the stack is true (non-zero). If the condition is false (0), another statement can be executed.

Try it

Syntax

wasm

i32.const 0
(if
  (then
    ;; do something
  )
  (else
    ;; do something else
  )
)

To leave return values on the stack, add the result statement.

wasm

i32.const 0
(if (result i32)
  (then
    ;; do something
    (i32.const 1)
  )
  (else
    ;; do something else
    (i32.const 2)
  )
)
(drop)

Instruction	Binary opcode
`if`	`0x04`
`else`	`0x05`