Update BinarySearch.js (#209)

* Update BinarySearch.js

The old algorithm didn't work, I believe for two main reasons:
1 -  Number.MAX_VALUE is not a valid array index as it is used to represent the highest possible value in javascript (https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/MAX_VALUE);

2 - splice() is not a pure function, every time it is called it has the side effect of modifying the original array (https://www.w3schools.com/jsref/jsref_splice.asp) ;

So I rewrote the algorithm, it now returns an index ( -1 if not found ) and it works both on numbers and on strings.

* Update BinarySearch.js

Style change

* Update BinarySearch.js

Style change

* Update BinarySearch.js