Set style of an element based on HTML attribute

Issue

I have a div with several child divs like this:

<div class=container>
  <div data-value="3">div 1</div>
  <div data-value="2">div 2</div>
  <div data-value="1">div 3</div>
  <div data-value="2">div 4</div>
</div>

I need to set the flex attribute of each to its data-value. I came up with this:

$('.container > div').css('flex', $(this).attr('data-value'));

but that doesn't work - probably because that's not how $(this) is used.

How do I fix this?

Solution

You don't need JS.

.container { display: flex; }
.container > * {  outline: 1px solid gold; }

[data-value]     { flex: 1; }  /* default to 1 */
[data-value="2"] { flex: 2; }
[data-value="3"] { flex: 3; }

<div class="container">
  <div data-value="3">div 1</div>
  <div data-value="2">div 2</div>
  <div data-value="1">div 3</div>
  <div data-value="2">div 4</div>
</div>

Or without hardcoding values — by using CSS var():

.container { display: flex; }
.container > * { flex: var(--flex); outline: 1px solid gold;  }

<div class="container">
  <div style="--flex:3">div 1</div>
  <div style="--flex:2">div 2</div>
  <div style="--flex:1">div 3</div>
  <div style="--flex:2">div 4</div>
</div>

If you totally need JavaScript - than you don't need jQuery

document.querySelectorAll("[data-value]").forEach(el => el.style.flex = el.dataset.value);

.container { display: flex; }
[data-value] { outline: 1px solid gold;  }

<div class="container">
  <div data-value="3">div 1</div>
  <div data-value="2">div 2</div>
  <div data-value="1">div 3</div>
  <div data-value="2">div 4</div>
</div>

If you totally need jQuery (— which you don't, in 2022):

$("[data-value]").css("flex", function () {
  return $(this).attr("data-value");
});

.container { display: flex; }
[data-value] { outline: 1px solid gold;  }

<div class="container">
  <div data-value="3">div 1</div>
  <div data-value="2">div 2</div>
  <div data-value="1">div 3</div>
  <div data-value="2">div 4</div>
</div>

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.6.0/jquery.min.js"></script>

Answered By - Roko C. Buljan