HTML & CSS
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By Guy Routledge

AtoZ CSS Screencast: The translateX CSS Property

By Guy Routledge

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This screencast is a part of our AtoZ CSS Series. You can find other entries to the series here.

Transcript

As we approach the end of the alphabet and the end of the first season of AtoZ CSS, there aren’t many properties, values or concepts that start with the letter X.

There are however a series of transform values that allow elements to have their visual coordinates changed along the x-axis to create complex and interesting visual details on the page.

In this episode we’ll learn all about:

  • The CSS transform property
  • Moving elements with translate and translateX
  • The performance benefits of using translate over other methods

transform

The transform property allows elements to be moved from their natural position in the document whilst maintaining that original space – a bit like the result of moving elements with position:relative.

Elements can be translated, rotated, scaled or skewed in various different ways on various different axes.

The transform property can take the following values:

  • matrix()
  • matrix3d()
  • translate()
  • translateX()
  • translateY()
  • translateZ()
  • translate3d()
  • scale()
  • scaleX()
  • scaleY()
  • scaleZ()
  • scale3d()
  • skew()
  • skewX()
  • skewY()
  • rotate()
  • rotateX()
  • rotateY()
  • rotateZ()
  • rotate3d()
  • perspective()

There’s a long list here and to be honest, I only use a small selection of them on day to day projects. It’s useful to know the other options but I most often use:

  • translate()
  • rotate()
  • scale()
  • and skew()

It’s also possible to chain multiple transform values together by creating a space separated list as follows:

.some-class {
  transform: scaleX(2) rotate(10deg);
}

This will double the horizontal scale of an element and rotate it 10 degrees clockwise.

translate

The translate value moves an element in 2D space.

I have an image here with a couple of paragraphs above and below it.

The translate function accepts one or two values. If two values are passed in, the first specifies the translation along the x-axis, the second for the y-axis.

img {
  transform: translate(10px,60px);
}

The values can be any valid length available in CSS. It could be px, em, rem, % etc.

If just one value is provided, the second value is assumed to be zero and so no y-axis translation takes place.

Using translateX we can be more explicit about the transformation we want to create as it’s very clear that this is only supposed to occur in the x-direction. If I only wanted this single-axis movement, translateX would be my preference as it’s always best to be clear about your intent when writing code.

Performance

When animating elements, there are benefits to animating the transform property over animating something like margin or top and left position.

When animating elements with transform, the processing is moved on to the graphical processing unit (GPU) rather than the CPU. The net result of this is that animations are smoother and they have less of an impact on perceived responsiveness and battery life.

For an in-depth and technical screencast that outlines these benefits really well, check out this video from Paul Irish titled “Why Moving Elements With Translate() Is Better Than Pos:abs Top/left”.

I found this to be the case first hand when I made the animation for AtoZ CSS – to begin with, I animated the margin-left property of the animation container but found this to be very slow. Moving to animating the container with translate, really improved the visual performance.

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