# JavaScript Scheduler | DayPilot Lite for JavaScript Demo

> You can customize the cells using the onBeforeCellRender event. Read more about [cell customization](https://javascript.daypilot.org/scheduler/cell-customization/).

## Links

- Canonical HTML: /demo/lite/scheduler/cellcustomization.html
- Source HTML folder: /demo/lite/scheduler/
- Catalog root: /demo/lite/
- Catalog: /demo/lite/llms.txt

## Source

### Inline demo script 1

```javascript
const dp = new DayPilot.Scheduler("dp", {
            startDate: "2026-04-01",
            days: 365,
            scale: "Day",
            timeHeaders: [
                {groupBy: "Month", format: "MMMM yyyy"},
                {groupBy: "Day", format: "d"}
            ],
            heightSpec: "Max",
            height: 400,
            cellWidth: 80,
            contextMenu: new DayPilot.Menu({
                items: [
                    {
                        text: "Edit",
                        onClick: async (args) => {
                            const result = await app.editEvent(args.source.data);
                            if (!result) {
                                return;
                            }
                            dp.events.update(result);
                        }
                    },
                    {
                        text: "-"
                    },
                    {
                        text: "Delete",
                        onClick: (args) => {
                            dp.events.remove(args.source);
                        }
                    },
                ]
            }),
            onTimeRangeSelected: async (args) => {
                const data = {
                    start: args.start,
                    end: args.end,
                    id: DayPilot.guid(),
                    resource: args.resource,
                    text: "New event"
                };
                const result = await app.editEvent(data);
                dp.clearSelection();
                if (!result) {
                    return;
                }
                dp.events.add(result);
            },
            onEventClick: async (args) => {
                const result = await app.editEvent(args.e.data);
                if (!result) {
                    return;
                }
                dp.events.update(result);
            },
            onBeforeCellRender: args => {
                args.cell.properties.text = args.cell.start.toString("MMM d");
                args.cell.properties.fontColor = "#ddd";
                args.cell.properties.verticalAlignment = "center";
                args.cell.properties.horizontalAlignment = "center";
            },

        });

        dp.init();
        dp.scrollTo("2026-04-01");

        const app = {
            async editEvent(data) {
                const form = [
                    { name: "Text", id: "text"},
                    { name: "Start", id: "start", type: "datetime", disabled: true },
                    { name: "End", id: "end", type: "datetime", disabled: true },
                    { name: "Resource", id: "resource", options: dp.resources}
                ];
                const modal = await DayPilot.Modal.form(form, data);
                if (modal.canceled) {
                    return null;
                }
                return modal.result;
            },
            loadData() {
                const resources = [
                  {name: "Room 1", id: "A"},
                  {name: "Room 2", id: "B"},
                  {name: "Room 3", id: "C"},
                  {name: "Room 4", id: "D"},
                  {name: "Person 1", id: "E"},
                  {name: "Person 2", id: "F"},
                  {name: "Person 3", id: "G"},
                  {name: "Person 4", id: "H"},
                  {name: "Tool 1", id: "I"},
                  {name: "Tool 2", id: "J"},
                  {name: "Tool 3", id: "K"},
                  {name: "Tool 4", id: "L"}
                ];

                dp.update({resources});
            },
        };

        app.loadData();
```