JavaScript smart contract function

Hello how i can display on JavaScript frontend this function result ? Win or lose
function bet(uint256 tokens) public returns (string memory) {
require(balances[msg.sender] >= tokens);
balances[msg.sender] = safeSub(balances[msg.sender], tokens);
emit Transfer(msg.sender, address(0), tokens);

bool won = random() % 2 == 0; // If the hash is even, the game is won
if(won) {
balances[msg.sender] = safeAdd(balances[msg.sender], safeMul(tokens, 2));
emit Transfer(address(0), msg.sender, safeMul(tokens, 2));
return 'You won!';
} else {
return 'You lost.';
}
}