JavaScript

• .. Operator

as E4X

var person = <person>
  <name>Bob Smith</name>
  <likes>
    <os>Linux</os>
    <browser>Firefox</browser>
    <language>JavaScript</language>
    <language>Python</language>
  </likes>
</person>;

alert(person.likes.*.length()); // 4
alert(person..*.length()); // 11
The length() method here returns 11 because both elements and text nodes are included in the resulting XMLList.

.. as decimal point

255..toString(16);

First dot is actually a decimal point, just let JavaScript Compiler know the second dot wants to invoke property or method. And255.toString(16)makes JavaScript Compiler confused(identifier starts immediately after decimal numeric literal).