```
/**
* @param {number} num
* @return {boolean}
*/
var isPowerOfFour = function(num) {
return /^1(00)*$/.test(num.toString(2));
};
```

- JavaScript does conversion to string representation of a binary number with toString(2). The number to the left requires parenthesis when using a literal number (which isn't the case here).
- The string must have an even number of zeros to the right of a 1 in the first position.