Minor edits to animation-in-canvas guide code (#31185)

* docs(guide): minor edits to animation-in-canvas

* Use ES6 syntax in code examples
* Clean up formatting in code examples for clarity
* Remove unnecessary sentence for brevity

* docs(guide): use arrow functions for canvas animation examples

guide/english/canvas/animation-in-canvas/index.md

@@ -6,26 +6,25 @@ title: Animation
 To animate things in `canvas`, use `window.requestAnimationFrame` to set up a draw loop.
 
 ```js
-function draw() {
+const draw = () => {
   /* code goes here */
   window.requestAnimationFrame(draw);
-}
+};
 window.requestAnimationFrame(draw);
 ```
 
-The below code will cause the `draw` function to be run every frame.
-
 `canvas` has no special functions that allow for animating. You just have to be used to writing in animation loops. The usual design paradigm for animation loops is to update the state, then draw the state. For instance, to draw a square moving across the screen:
 
 ```js
-canvas = document.getElementById("canvas");
-ctx = canvas.getContext('2d');
+const canvas = document.getElementById('canvas');
+const ctx = canvas.getContext('2d');
 
-var x=0;
-var y=50;
-function draw() {
+const y = 50;
+let x = 0;
+const draw = () => {
   // reset canvas
   ctx.clearRect(0, 0, canvas.width, canvas.height);
+
   // update state
   x += 1;
 
@@ -35,11 +34,11 @@ function draw() {
   ctx.fill();
 
   window.requestAnimationFrame(draw);
-}
+};
 window.requestAnimationFrame(draw);
 ```
 
-To see this concept in action, see the '[Particle Sim](/articles/canvas/particle-sim)' page.
+To see this concept in action, see the [Particle Sim](/articles/canvas/particle-sim) page.
 
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