Dependencies

A dependency links two tasks so that one is scheduled relative to the other. FluxGantt supports all four classic dependency types plus a lag/lead offset.

Dependency types

DependencyType is one of:

Type	Name	Meaning
`FS`	Finish-to-Start	`to` starts after `from` finishes. The default.
`SS`	Start-to-Start	`to` starts after `from` starts.
`FF`	Finish-to-Finish	`to` finishes after `from` finishes.
`SF`	Start-to-Finish	`to` finishes after `from` starts (rare).

Declaring dependencies up front

Pass them to createGantt as { from, to, type?, lag? } (a DependencyInput). from/to are TaskIds:

import { createGantt, toTaskId } from '@fluxgantt/core';
 
const gantt = createGantt({
  tasks: [/* … */],
  dependencies: [
    { from: toTaskId('design'), to: toTaskId('build'), type: 'FS' },
    { from: toTaskId('build'), to: toTaskId('review'), type: 'FS' },
  ],
});

type defaults to 'FS' when omitted. An invalid initial set (a self-link, a duplicate pair, or a cycle) throws at construction — FluxGantt rejects bad data rather than best-effort loading it.

Linking at runtime

// linkTasks(from, to, type?, lag?) → Dependency, emits dependency:added
const dep = gantt.linkTasks(toTaskId('review'), toTaskId('launch'), 'FS');
 
// unlinkTasks(from, to) → void, emits dependency:removed
gantt.unlinkTasks(toTaskId('review'), toTaskId('launch'));
 
// inspect
gantt.getDependencies();                    // Dependency[]
gantt.getDependenciesOf(toTaskId('build')); // links touching a task

A Dependency you get back has a generated id: DependencyId, plus from, to, type, and optional lag.

Lag and lead

lag is measured in hours. A positive lag is a wait; a negative lag is lead time (overlap):

// build starts 8 working hours AFTER design finishes
gantt.linkTasks(toTaskId('design'), toTaskId('build'), 'FS', 8);
 
// review can start 4 hours BEFORE build finishes (lead / overlap)
gantt.linkTasks(toTaskId('build'), toTaskId('review'), 'FS', -4);

Cycles are rejected

FluxGantt refuses to create a dependency that would introduce a cycle — linkTasks throws, and a cyclic initial dependencies array throws at construction. This guarantees the critical-path computation always terminates. See Critical Path.

Creating dependencies by dragging

When the chart is mounted (and not readOnly), a user can drag from one task's link handle to another to create an FS dependency — this emits dependency:added, exactly like linkTasks. See Drag & Drop.