It’s made its way back in Svelte. It is used to make statements reactive.
Reactivity is not new to software engineering, anybody with basics of Excel knows it.
For example this simple function below makes B3 react to changes in B1 or B2
Here is a Svelte implementation of the same thing, notice line 5 and the usage of $: that makes sumOfTwo react to changes in val1 or val2. Internally Svelte is using JavaScript’s label syntax
If you want to edit and try the REPL here
This also works across different components using Svelte stores, but how stores work is worth going through in another post. Now, go fix some bugs!
TechSpark 