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beforeAdd

Description​

Fires before adding an item

Usage​

beforeAdd: (newItem: object) => boolean | void;

Parameters​

The callback of the event takes the following parameter:

  • newItem - (required) the object of an added item

Returns​

Return false to prevent adding an item into a data collection; otherwise, true

Example​

// initializing Diagram
const diagram = new dhx.Diagram("diagram_container", {
    type: "default"
});
// loading data
diagram.data.parse(data);

// attaching a handler to the event
diagram.events.on("beforeAdd", (newItem) => {
    if (some_check)
        return false;
    return true;
});