Packing binary data in JavaScript

Question

If I have unpacked binary data

1700885369 # translates to 'easy'

How can I get back to a byte array (most preferably without importing anything)? Like Python's struct.Struct(format).pack:

>>> import struct
>>> s = struct.Struct('>1I') # a big-endian, two-byte, unsigned int
>>> s.pack(1700885369)
b'easy' # bytearray([101, 97, 115, 121])

Guffa · Accepted Answer · 2015-04-14 23:49:28Z

1

You can get a byte at a time from the value and put in an array:

var value = 1700885369;
var arr = [];
while (value > 0) {
  arr.unshift(value % 256);
  value = Math.floor(value / 256);
}

// display value in StackOverflow snippet
document.write(arr);

answered Apr 14, 2015 at 23:49

Guffa

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