block

(module ;; import the browser console object, you'll need to pass this in from JavaScript (import "console" "log" (func $log (param i32))) ;; create a function that takes in a number as a param, ;; and logs that number if it's not equal to 100. (func (export "log_if_not_100") (param $num i32) (block $my_block ;; $num is equal to 100 local.get $num i32.const 100 i32.eq (if (then ;; branch to the end of the block br $my_block ) ) ;; not reachable when $num is 100 local.get $num call $log ) ) ) 

const url = "{%wasm-url%}"; await WebAssembly.instantiateStreaming(fetch(url), { console }).then( (result) => { const log_if_not_100 = result.instance.exports.log_if_not_100; log_if_not_100(99); // Expected output: 99 log_if_not_100(100); // Should not log anything log_if_not_100(101); // Expected output: 101 }, ); 

;; label the block so that it can be branched to. (block $my_block ;; branch to the block. ;; most of the time you'll want to put this in an if statement and only branch on condition, ;; otherwise the following control flow are unreachable. br $my_block ;; this will never be reached, since the br jumped out of the block already. unreachable )