# JavaScript Scheduler | DayPilot Lite for JavaScript Sandbox

> Customize the component using [Scheduler UI Builder](https://builder.daypilot.org/scheduler) and download a ready-to-run project. Read more about the [JavaScript scheduler](https://javascript.daypilot.org/scheduler/).

## Links

- Canonical HTML: /sandbox/lite/scheduler/index.html
- Source HTML folder: /sandbox/lite/scheduler/
- Catalog root: /sandbox/lite/
- Catalog: /sandbox/lite/llms.txt

## Source

### Inline demo script 1

```javascript
const dp = new DayPilot.Scheduler("dp", {
            startDate: "2026-09-01",
            days: 365,
            scale: "Day",
            timeHeaders: [
                {groupBy: "Month", format: "MMMM yyyy"},
                {groupBy: "Day", format: "d"}
            ],
            heightSpec: "Max",
            height: 400,
            rowMarginTop: 2,
            rowMarginBottom: 2,
            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);
            },
            onBeforeEventRender: args => {
                args.data.areas = [
                    {
                        right: 2,
                        top: "calc(50% - 9px)",
                        width: 18,
                        height: 18,
                        style: "cursor:pointer;",
                        backColor: "#cccccc66",
                        borderRadius: "50%",
                        padding: 2,
                        fontColor: "#333333",
                        symbol: "../icons/daypilot.svg#threedots-h",
                        action: "ContextMenu",
                        toolTip: "Menu"
                    }
                ];
            },
        });

        dp.init();
        dp.scrollTo("2026-09-01");

        const app = {
            barColor(i) {
                const colors = ["#3c78d8", "#6aa84f", "#f1c232", "#cc0000"];
                return colors[i % 4];
            },
            barBackColor(i) {
                const colors = ["#a4c2f4", "#b6d7a8", "#ffe599", "#ea9999"];
                return colors[i % 4];
            },
            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"}
                ];

                const events = [];
                for (let i = 0; i < 12; i++) {
                    const duration = Math.floor(Math.random() * 6) + 1; // 1 to 6
                    const durationDays = Math.floor(Math.random() * 6) + 1; // 1 to 6
                    const start = Math.floor(Math.random() * 6) + 2; // 2 to 7

                    const e = {
                        start: new DayPilot.Date("2026-09-05T12:00:00").addDays(start),
                        end: new DayPilot.Date("2026-09-05T12:00:00").addDays(start).addDays(durationDays).addHours(duration),
                        id: i + 1,
                        resource: String.fromCharCode(65 + i),
                        text: "Event " + (i + 1),
                        barColor: app.barColor(i),
                        barBackColor: app.barBackColor(i)
                    };

                    events.push(e);
                }

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

        app.loadData();
```