Math.trunc(n) != n) {
throw new Error("不能是负的，且必须是整数。");
}
return n <= 1 ? n : fib(n - 1) + fib(n - 2);
}
let start = Date.now();
try {
result = fib(num);
} catch(e) {
result = 0;
} finally {
diff = Date.now() - start;
}
alert(result
关键词：js try ... catch语法结构有啥用？try ... catch详细说明