Leaflet plus turf.js - color of line before & after point - leaflet

Question

I have a basic leaflet plus turf.js polyline - i'd like to be able to style the line before and after a given point. So for example - from the start to the point marker (along) (color : red). Basically, showing the portion of the route(line) that has been completed.
//path coords
var coords = [
[-3.535,55.62],
[-3.54,55.61],
[-3.547,55.6],
[-3.55,55.59],
[-3.57,55.58]
];
var features = turf.points(coords );
var center = turf.center(features);
var map = L.map('map');
L.tileLayer(
'https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png', {
attribution: '© <a href="https://openstreetmap.org" target=blank>OpenStreetMap</a> Contributors',
maxZoom: 18,
}).addTo(map);
var line = turf.lineString(coords);
var options = {units: 'miles'};
L.geoJSON(line).addTo(map);
var along = turf.along(line, 1.25, options);
L.geoJSON(along).addTo(map).bindTooltip("my tooltip text");
// get center x/y
var features = turf.points(coords);
var center = turf.center(features);
var centroid_xy = center.geometry.coordinates;
var x = centroid_xy[0];
var y = centroid_xy[1];
// get bounds
var bbox = turf.bbox(line);
var b0 = bbox[0];
var b1 = bbox[1];
var b2 = bbox[2];
var b3 = bbox[3];
L.marker([55.62, -3.535]).bindPopup("Test marker").addTo(map);
var mapMarker2 = L.icon({
iconSize: [16, 16],
iconAnchor: [8, 8],
});
map.setView([y, x], 13);
map.fitBounds([[b1, b0],[b3, b2]]);

Answer 1

You can use your along point to split the line with TurfJS:
split = turf.lineSplit(line, along)
This gives you a FeatureCollection of 2 features, which you can use to show the two segments on the map.
https://observablehq.com/d/f379582399e8089d