What is css guard?

Question

css

Hello.
I googled, honestly, but did not find the answer.
I'm assuming it's some sort of security feature?

Answer 1

I haven't heard about css guards, but they are in the less preprocessor. In fact, these are conditions, the fulfillment or non-fulfillment of which leads to different results. A simple example from the less documentation:

.mixin(@a) when (@media = mobile) { ... }
.mixin(@a) when (@media = desktop) { ... }

The conditions inside when are guards. Another example is a loop (in fact, there are no loops in less, but there is a recursion, which guard helps to get out of).
.

loop(@counter) when (@counter > 0) {
  .loop((@counter - 1));    // next iteration
  width: (10px * @counter); // code for each iteration
}