onBeforeTaskMultiSelect

fires before the task selection state is being changed (the task is being selected or unselected)

void onBeforeTaskMultiSelect(string|number id,boolean state,Event|null e);

id	string\|number	the id of a task
state	boolean	true if the task is going to be selected, false - if unselected
e	Event\|null	a native event object

Example

gantt.attachEvent("onBeforeTaskMultiSelect", function(id, state, e){
    // some logic here
     return true;
});

Details

This event is defined in the multiselect extension, so you need to activate the multiselect plugin. Read the details in the Multi-Task Selection article.

The event is called for each task of the range.

The event is blockable, returning false will cancel the change of the task selection state.