如何在Javascript中将两个8位转换为16位，反之亦然？

Question

I know this has been asked before, but I have not been able to reach a solution. I apologize if the topic is duplicated, but I think it's not.

I have a number extracted from a Uint16Array to convert to a pair of 8-bit numbers and does it well, but when I want to convert from these two 8-bit numbers to the the first number I can't get it.

 var firstNumber = 1118; // extracted from Uint16Array var number8Bit1 = firstNumber & 0xff; var number8Bit2 = ((firstNumber >> 8) & 0xff); console.log(number8Bit1, number8Bit2); // 94, 4 var _firstNumber = (((number8Bit1 & 0xff) << 8) | (number8Bit2 & 0xff)); console.log(_firstNumber); // 24068 <-- 1118 

You would be so kind as to help me please. Thank you.

Answer 1

You swapped the bytes:

var _firstNumber = (((number8Bit2 & 0xff) << 8) | (number8Bit1 & 0xff));

You have to do the reverse of the extraction when combining.

var firstNumber = 1118; // extracted from Uint16Array

var high = ((firstNumber >> 8) & 0xff);
var low = firstNumber & 0xff;

console.log(high, low); // 4, 94

var _firstNumber = (((high & 0xff) << 8) | (low & 0xff));

console.log(_firstNumber); // 1118