Alternative for JavaScript Math Range?

Question

I saw this gist to change RGB color to RGBA, but JS Math does not have a range method. Is there any way to convert the range method here?

function rgba(hex, opacity) {
    var colours = hex.regex(/#?([0-9A-F]{2})([0-9A-F]{2})([0-9A-F]{2})/i).map(function(val) {
        return Math.range(0, parseInt(val, 16), 255);
    }).join(",");
    if (opacity === undefined) {
        return "rgb(" + colours + ")";
    }
    return "rgba(" + colours + "," + opacity + ")";
}

Found this here: https://gist.github.com/Rycochet/8597336

Hi, http://mathjs.org/docs/reference/functions/range.html ?? — The Segfault, Jan 24 '18 at 14:49
thanks @AlexyHody. I am trying to stay away from any 3rd party. Just want to be able to do this with regular JS. — pertrai1, Jan 24 '18 at 14:51
If you looked at Rycochet's other gists, you'd find [the source](https://gist.github.com/Rycochet/8597399) with ease. — Nick is tired, Jan 24 '18 at 15:12
@ScottSauyet indeed, that source can be found [here](https://gist.github.com/Rycochet/8597361) — Nick is tired, Jan 24 '18 at 15:28
@NickA: Sorry, missed some of the discussion. This is not how I would choose to solve the problem, but it certainly works. — Scott Sauyet, Jan 24 '18 at 15:42

score 2 · Answer 1 · answered Jan 24 '18 at 14:52

2

It appears to me that range method just clamps the value. You can do that by combining max and min methods.

Math.range = function(min, val, max) {
  return Math.max(min, Math.min(val, max));
};

answered Jan 24 '18 at 14:52

kamoroso94

1,713
1
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Or `var clamp = (min, val, max) => val < min ? min : val > max ? max : val`. `range` is an odd name for this function. I've usually seen `range(3, 6) //=> [3, 4, 5, 6]` or some variant of it.. – Scott Sauyet Jan 24 '18 at 15:15

ild flue · Accepted Answer · 2018-01-24T14:57:41.247

1

To fulfill the color conversion without range

function rgba(hex, opacity) {
    var colours = hexToRgb(hex);
    if (opacity === undefined) {
        return "rgb(" + colours + ")";
    }
    return "rgba(" + colours + "," + opacity + ")";
}

function hexToRgb(hex) {
    var bigint = parseInt(hex, 16);
    var r = (bigint >> 16) & 255;
    var g = (bigint >> 8) & 255;
    var b = bigint & 255;

    return r + "," + g + "," + b;
}

The function hexToRgb(hex) was from RGB to Hex and Hex to RGB

edited Jan 24 '18 at 14:57

answered Jan 24 '18 at 14:47

ild flue

1,323
8
9

thank you for the response. In regards to the way that `Math.range` is being used in this case, how would I convert that to not be using `range` – pertrai1 Jan 24 '18 at 14:50
I updated it with a code to fulfill the color conversion without `range` – ild flue Jan 24 '18 at 15:00

Alternative for JavaScript Math Range?

2 Answers2