convert hex to binary in javascript

Question

I need to convert hex into binary using javascript.

example: 21 23 00 6A D0 0F 69 4C E1 20

should result in: ‭0010000100100011000000000110101011010000000011110110100101001100‬

Does anyone know of a javascript library I might use to accomplish this?

Harriet

Answer 1

You can create a function converting a hex number to binary with something like this :

function hex2bin(hex){
    return ("00000000" + (parseInt(hex, 16)).toString(2)).substr(-8);
}

For formatting you just fill a string with 8 0, and you concatenate your number. Then, for converting, what you do is basicaly getting a string or number, use the parseInt function with the input number value and its base (base 16 for hex here), then you print it to base 2 with the toString function. And finally, you extract the last 8 characters to get your formatted string.

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2018 Edit :

As this answer is still being read, I wanted to provide another syntax for the function's body, using the ES8 (ECMAScript 2017) String.padStart() method :

function hex2bin(hex){
    return (parseInt(hex, 16).toString(2)).padStart(8, '0');
}

Using padStart will fill the string until its lengths matches the first parameter, and the second parameter is the filler character (blank space by default).

End of edit

---

To use this on a full string like yours, use a simple forEach :

var result = ""
"21 23 00 6A D0 0F 69 4C E1 20".split(" ").forEach(str => {
  result += hex2bin(str)
})
console.log(result)

The output will be :

00100001001000110000000001101010110100000000111101101001010011001110000100100000

Answer 2

You can use parseInt and toString to change the radix of a number.

function convertNumber(n, fromBase, toBase) {
  if (fromBase === void 0) {
    fromBase = 10;
  }
  if (toBase === void 0) {
    toBase = 10;
  }
  return parseInt(n.toString(), fromBase).toString(toBase);
}
console.log(
  convertNumber("f", 16, 10),
  convertNumber("f", 16, 2),
  convertNumber("1111", 2, 10),
  convertNumber("1111", 2, 16)
);