How to get hex integer from a string in JS?

Question

I would like to convert this: "#FFFFFF" to this: 0xFFFFFF. How is it possible without using eval?

Thanks in advance,

I am sure this is a duplicate... I wish the "related questions" were smarter about language tags :-/ — user166390
– user166390, Commented Apr 23, 2012 at 21:19
@ Danny: By "hex value," do you mean the numeric value FFFFFF hex (e.g., 16777215 decimal?). If so, just say "numeric value," putting the word "hex" in takes us into string land. I think you probably meant numeric, though. — T.J. Crowder
– T.J. Crowder, Commented Apr 23, 2012 at 21:28
I have just answered a similar question here: stackoverflow.com/questions/48140695/… — 8urning8eard
– 8urning8eard, Commented Jan 6, 2022 at 13:43

Mike 'Pomax' Kamermans · Accepted Answer · 2019-06-13 00:37:20Z

59

Strip off the "#" and use parseInt().

var hex = parseInt(str.replace(/^#/, ''), 16);

Then, if you want to see it in hex, you can use .toString():

console.log(hex.toString(16));

edited Jun 13, 2019 at 0:37

Mike 'Pomax' Kamermans

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answered Apr 23, 2012 at 21:17

Pointy

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6 Comments

Mark Reed Over a year ago

I would prefer substring() (as in @TJCrowder's answer) over replace(), for efficiency's sake.

T.J. Crowder Over a year ago

@MarkReed: It totally depends on what the OP really wants, which isn't clear from the question. It may be (given the lack of quotes on 0xFFFFFF) that the OP wants then numeric value (which, of course, would make the title of the question completely wrong -- not the first time!).

Mark Reed Over a year ago

@TJCrowder: Your reply seems to be on the wrong answer. :) All I said above was that I would use substring(1) instead of replace(regex) for this problem.

Pointy Over a year ago

@Displee yes it does?

Displee Over a year ago

@Pointy parseInt("#797e61".replace(/^#/, ''), 16); gives me 7962209 as result, and not 0x797e61.

|

Garry Ho · Accepted Answer · 2020-03-10 02:57:14Z

0

Use this code:

var resultP = document.getElementById('result');
var btn = document.querySelector('button');
var input = document.querySelector('input');
function convert(hex) {
  return Number(`0x${hex.substr(1)}`);
}
btn.addEventListener('click', () => {
  resultP.innerHTML = convert(input.value);
})

* {
  font-family: Arial;
}

<!DOCTYPE html>
<html>
  <head>
    <title>Hex code to hex integer</title>
    <meta charset="UTF-8" />
  </head>
  <body>
    <input type="text" maxlength="7" />
    <button>Done</button>
    <br />
    Result:
    <p id="result"></p>
  </body>
</html>

answered Mar 10, 2020 at 2:57

Garry Ho

91 bronze badge

1 Comment

bad_coder Over a year ago

It's desirable that you give a brief explanation how the code solves the problem in the question.

Sam Mulqueen · Accepted Answer · 2023-04-16 03:30:02Z

0

You could try this code:

function hex2num(hexcode){ return Number(  '0x' + hexcode.split(/[^0-9a-fA-F]+/).join('')  ) }

This function will strip out all characters that are not numbers between 0-9 or alphabetical characters between A-F before trying to parse the input. The output is a number, because 0x009 === 9 in JS.

This solution works when dealing with numbers that are less than the MAX SAFE INTEGER (9007199254740991) but if the hex code equates to a number larger than that you will probably need to use a different solution.

Expected Usage:

hex2num('#0000FF') === 255 // true

hex2num('#FFFFFF') === 16777215 // true

hex2num('0x000000000001') === 1 // true

hex2num('0L0L4') === 4 // true

edited Apr 16, 2023 at 3:30

answered Apr 16, 2023 at 2:59

Sam Mulqueen

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