css-send

quick few lines of code made to make my life a teeny bit easier by using javascript to send data to css variables. i don't intend to formalize this unless it like randomly blows up but have some helpful tips below. feedback always accepted

how to use

its pretty easy just go to css-send.js and copy paste the javascript into your file. its pretty simple just sends scroll data to css variables

Current variables

--scroll: The current javascript window.scrollY value (there's no scrollX sorry unless you bug me about it)

--scroll-percent: A number between 0 and 100 of the current scroll percentage.

--lastClickX: The most recent click location in pixels relative to the window (or whatever math javascript does)

--lastClickY: Same thing as above but on the Y axis instead

--lastMouseX: Similar to lastClickX, except triggers on mouse movement and gets the current position of the mouse

--lastMouseY: Same thing as above but on the Y axis instead

Conditionals

These are probably very janky and might slow down visible rendering so use at your own risk but so far they work pretty well in the small-scale contexts I have tried them in. To use a conditional css variable, create your variable (preferably in :root since thats where the JS will send the data anyway) using ternaries prefixed by eval to let the JS know its an equation. This is best described using an example, so below is an example of a div that changes background color based on scroll position. For javascript variables, use the css variables but styled in a javscript way i guess? scroll, lastClickX, etc.

:root{
  --bg: "eval(scroll > 100 ? 'blue' : 'green')"
}

div{
  background-color: var(--bg, green)
}

Might be helpful to know...

Since this only sends numbers without a unit, in css you can convert number to units by doing calc(var(--var-name) * 1un) where un is your desired unit

(more to be added as and when needed)

To Do

• Better communication between CSS and JS
• Optimize update()
• Send movement data from JS to CSS