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How do I swap endian-ness (byte order) of a variable in javascript

Asked 2011-03-16T02:37:36.110
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I am receiving and sending a decimal representation of two little endian numbers. I would like to:

  • shift one variable 8 bits left
  • OR them
  • shift a variable number of bits
  • create 2 8 bit numbers representing the first and second half of the 16 bit number.

javascript (according to https://developer.mozilla.org/en/JavaScript/Reference/Operators/Bitwise_Operators) uses big endian representation when shifting...

endianness is a bit foreign to me (I am only 90 percent sure that my outlined steps are what i want.) so swapping is a bit dizzying. please help! I only really need to know how to swap the order in an efficient manner. (I can only think of using a for loop on a toString() return value)

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Use the << (bit shift) operator. Ex: 1 << 2 == 4.

I really think that the underlying implementation of JavaScript will use whatever endianess the platform it is running on is using. Since you cannot directly access memory in JavaScript you won't ever have to worry about how numbers are represented physically in memory. Bit shifting integer values always yield the same result no matter the endianess. You only see a difference when looking at individual bytes in memory using pointers.

answered 2011-03-16T03:07:20.717

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