Skip to main
Article

Map-Set vs. Map-Merge

The difference between map-set and map-merge? Almost nothing.

When I first heard that Sass 3.3 had no map-set function, I was confused. Why force me to create a map, and then merge it? That sounds like two steps to accomplish one simple task! But that’s not the case. Map-merge is a much more powerful function, and using it to set a key in an existing map is quite straight-forward. In fact, I couldn’t come up with a map-set function that shaved off more than a few keystrokes. Here’s the comparison:

// a map!
$map: (
  1: hello,
  2: world,
);

// a map-set function (not included with Sass)
@function map-set($map, $key, $value) {
  $new: (
    $key: $value,
  );
  @return map-merge($map, $new);
}

// the difference between map-set and map-merge: almost nothing.
$merge: map-merge(
  $map,
  (
    2: New York,
  )
);
$set: map-set($map, 2, New York);

Recent Articles

  1. A case of letterpress type with arrows pointing outward and a cursor hand overlaid
    Article post type

    Reimagining Fluid Typography

    Are we responding to the right inputs?

    For many years, it has been ‘best practice’ to use relative units (especially em and rem) for sizing text. That’s great! But after playing around with my user preferences, I think we can improve on the common approaches.

    see all Article posts
  2. A weathered small boat in the fog, with ropes going into the water, hopefully leading to an anchor.
    Article post type

    Here’s Why Your Anchor Positioning Isn’t Working

    How to find an anchor element

    It is frustrating to track down why an anchor isn’t being found. I’ve found a simple way that should work in most cases. If that doesn’t work, step through the checklist, and then dive in to get a better understanding of how Anchor Positioning works.

    see all Article posts
  3. A symmetrical knot with thick rope lying on weathered wood.
    Article post type

    Anchor Positioning Is Disruptive

    New layouts will be possible

    The more I play with it, the more convinced I am that anchor positioning is going to unlock some surprising new layouts.

    see all Article posts