```js  
  var a = (10 * 3 - 4 / 2 + 1) % 2;
    b = 3;
    b %= a + 3;
    var d = a++ - b;
    document.write(a++);
    document.write("</br>");
    document.write(--b);
    document.write("</br>");

我們這里有一段

   var a = 123;
    b = 234;
    a = a + b;
    b = a - b;
    a = a - b;
    document.write(a, b)