Whereas You Weren’t Trying, CSS Gradients Bought Higher


One factor that caught my eye on the checklist of features for Lea Verou’s conic-gradient() polyfill was the final merchandise:

Helps double place syntax (two positions for a similar shade cease, as a shortcut for 2 consecutive shade stops with the identical shade)

Surprisingly, I just lately found most individuals aren’t even conscious that double place for gradient stops is one thing that really exists within the spec, so I made a decision to put in writing about it.

In accordance with the spec:

Specifying two places makes it simpler to create solid-color “stripes” in a gradient, with out having to repeat the colour twice.

I fully agree, this was the very first thing I considered once I turned conscious of this function.

For example we need to get the next end result: a gradient with a bunch of equal width vertical stripes (which I picked up from an earlier post by Chris):

Desired gradient end result.

The hex values are: #5461c8, #c724b1, #e4002b, #ff6900, #f6be00, #97d700, #00ab84 and #00a3e0.

Let’s first see how we would CSS this with out utilizing double cease positions!

Now we have eight stripes, which makes every of them one-eighth of the gradient width. One eighth of 100% is 12.5%, so we go from one to the subsequent at multiples of this worth.

This implies our linear-gradient() seems as follows:

linear-gradient(90deg, 
             #5461c8 12.5% /* 1*12.5% */, 
  #c724b1 0, #c724b1 25%   /* 2*12.5% */, 
  #e4002b 0, #e4002b 37.5% /* 3*12.5% */, 
  #ff6900 0, #ff6900 50%   /* 4*12.5% */, 
  #f6be00 0, #f6be00 62.5% /* 5*12.5% */, 
  #97d700 0, #97d700 75%   /* 6*12.5% */, 
  #00ab84 0, #00ab84 87.5% /* 7*12.5% */, 
  #00a3e0 0)

Word that we needn’t repeat cease place % values as a result of, at any time when a cease place is smaller than a earlier one, we mechanically have a pointy transition. That is why it is all the time secure to make use of 0 (which is all the time going to be smaller than any optimistic worth) and have #c724b1 25%, #e4002b 0 as an alternative of #c724b1 25%, #e4002b 25%, for instance. That is one thing that may make our life simpler sooner or later if, for instance, we determine we need to add two extra stripes and make the cease positions multiples of 10%.

Not too dangerous, particularly in comparison with what gradient turbines usually spit out. But when we determine a kind of stripes within the center does not fairly slot in with the others, then altering it to one thing else means updating in two locations.

Once more, not too dangerous and nothing we won’t get round with a bit of little bit of assist from a preprocessor:

$c: #5461c8 #c724b1 #e4002b #ff6900 #f6be00 #97d700 #00ab84 #00a3e0;

@operate get-stops($c-list) {
  $s-list: ();
  $n: size($c-list);
  $u: 100%/$n;
	
  @for $i from 1 to $n {
    $s-list: $s-list, 
             nth($c-list, $i) $i*$u, 
             nth($c-list, $i + 1) 0
  }

  @return $s-list
}

.strip {
  background: linear-gradient(90deg, get-stops($c)))
}

This generates the precise CSS gradient we noticed a bit earlier and now we do not have to change something in two locations anymore.

See the Pen by thebabydino (@thebabydino) on CodePen.

Nevertheless, even when a preprocessor can save us from typing the identical factor twice, it does not get rid of repetition from the generated code.

And we could not all the time need to use a preprocessor. Leaving apart the truth that some persons are cussed or have an irrational worry or hate in the direction of preprocessors, it typically feels a bit foolish to make use of a loop.

For instance, once we barely have something to loop over! For example we need to get a a lot easier background sample, resembling a diagonal hashes one, which I would think about is a way more widespread use case than an over-the-top rainbow one which’s in all probability not a very good match on most web sites anyway.

Screenshot. Shows a pattern of diagonal light grey hashes on a white background.
Desired hashes end result

This requires utilizing repeating-linear-gradient() and this implies a little bit of repetition, even when we do not have the identical lengthy checklist of hex values as we did earlier than:

repeating-linear-gradient(-45deg, 
    #ccc /* cannot skip this, repeating gradient will not work */, 
    #ccc 2px, 
    clear 0, 
    clear 9px /* cannot skip this both, tells the place gradient repetition begins */)

Right here, we can not ditch the primary and final stops as a result of these are exactly what point out how the gradient repeats throughout the rectangle outlined by the background-size.

If you wish to perceive why it is higher to make use of repeating-linear-gradient() as an alternative of a plain previous linear-gradient() mixed with the right background-size so as to create such hashes, try this different article I wrote some time in the past.

That is exactly the place such function involves the rescue — it permits us to keep away from repetition within the remaining CSS code.

For the rainbow stripes case, our CSS turns into:

linear-gradient(90deg, 
    #5461c8 12.5%, 
    #c724b1 0 25%, 
    #e4002b 0 37.5%, 
    #ff6900 0 50%, 
    #f6be00 0 62.5%, 
    #97d700 0 75%, 
    #00ab84 0 87.5%, 
    #00a3e0 0)

And to recreate the hashes, we solely want:

repeating-linear-gradient(-45deg, 
    #ccc Zero 2px, 
    clear Zero 9px)

See the Pen by thebabydino (@thebabydino) on CodePen.

What about assist? Properly, glad you requested! It really occurs to be fairly good! It really works in Safari, Chromium browsers (which now contains Edge as nicely!) and Firefox. Pre-Chromium Edge and perhaps some cellular browsers might nonetheless maintain you again, but when you do not have to fret about offering assist for each browser below the solar or it is superb to supply a fallback, go forward and begin utilizing this!



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