How can I reference a variable from a js script in html

Question

I've seen similar questions asked before but none of them really helped in my situation. To boil it down I, a noobie, am trying to change an html background color to a variable that was created in a js script and I'm not sure quite how to do this. I want "color" to be used for the background color. h, m, s are hours minutes and seconds. I'm pulling these from the computer and it is working fine printing it. Here is something I found that is nearly identical to what I want to do www.jacopocolo.com/hexclock/

JS

if (h<=9) {h = '0'+h};
if (m<=9) {m = '0'+m};
if (s<=9) {s = '0'+s};

var color = '#'+h+m+s;

$("div.background").css("background-color", color );

HTML

<style>
.background {
width: 100%;
height: 100%;
position: absolute;
vertical-align: middle;
}
</style>

I've tried making a div for the background (shown above) but it doesn't seem to be working. In the end all I'm really set on is this part of it

if (h<=9) {h = '0'+h};
if (m<=9) {m = '0'+m};
if (s<=9) {s = '0'+s};

var color = '#'+h+m+s;

Can someone tell me how to properly do this or even just point me in the general direction? Any help would be greatly appreciated.

1 ) what is h , m ,s ?? are they inistialized by any value 2) are you sure the script is well linked !! — PacMan
– PacMan, Commented Apr 20, 2016 at 22:58
Debug your program and check if color has the expected value before using it. — Little Santi
– Little Santi, Commented Apr 20, 2016 at 23:01

CY_ · Accepted Answer · 2016-04-20 23:02:45Z

1

I tried it, and it works fine.

$(document).ready(function(){
    var h = 0;
    var m = 9;
    var s = 20;

    if (h<=9) {h = '0'+h}
    if (m<=9) {m = '0'+m};
    if (s<=9) {s = '0'+s};

    var color = '#'+h+m+s;

    console.log('color' + color);
    console.log("Original Color " + $("div.background").css('background-color'));

    $("div.background").css("background-color", color );

    console.log("Updated Color " + $("div.background").css('background-color'));
});

<html>
    <title>Title</title>
    <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.2.0/jquery.min.js"></script>
    <script src="app.js"></script>
    <style>
        .background {
            width: 100%;
            height: 100%;
            position: absolute;
            vertical-align: middle;
        }
    </style>
    </head>
<body>
    <div class="background">hello world</div>
</body>
</html>

answered Apr 20, 2016 at 23:02

CY_

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1 Comment

cdm Over a year ago

Since hours go from 0 to 23 and colors go from 0 to 255, I suggest adding h = Math.round(256/24 * h);, m = Math.round(256/60 * m); and s = Math.round(256/60 * s);

Little Santi · Accepted Answer · 2016-04-21 06:21:46Z

0

The problem in your code is probably that a color parameter pre-pended with '#' must be given in hexadecimal coordinates:

red=10, green=20 and blue=40 should be written like this:

#0A1428

So, you have to convert first to hexadecimal each coordinate like this:

var h = h.toString(16);
var m = m.toString(16);
var s = s.toString(16);

Then, perform the zero left-padding, and so.

answered Apr 21, 2016 at 6:21

Little Santi

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