I have noticed that PHP and JavaScript treat octal and hexadecimal numbers with some difficulty while type juggling and casting:

PHP:

```
echo 16 == '0x10' ? 'true' : 'false'; //true, as expected
echo 8  == '010'  ? 'true' : 'false'; //false, o_O

echo (int)'0x10';    //0, o_O
echo intval('0x10'); //0, o_O
echo (int)'010';     //10, o_O
echo intval('010');  //10, o_O

```

JavaScript:

```
console.log(16 == '0x10' ? 'true' : 'false'); //true, as expected
console.log(8  == '010'  ? 'true' : 'false'); //false, o_O

console.log(parseInt('0x10')); //16, as expected
console.log(parseInt('010'));  //8, as expected
console.log(Number('0x10'));   //16, as expected
console.log(Number('010'));    //10, o_O

```

I know that PHP has the `octdec()` and `hexdec()` functions to remedy the octal/hexadecimal misbehaviour, but I'd expect the `intval()` to deal with octal and hexadecimal numbers just as JavaScript's `parseInt()` does.

Anyway, what is the rationale behind this odd behaviour?