# mpxj-ts

The Microsoft Project file reader behind johnmcm.com's MPP Viewer
(https://johnmcm.com/mpp-viewer). It reads, in the browser:

- `.mpp` and `.mpt` files from Microsoft Project 2010 to 2024 (the "MPP14"
  format): a TypeScript port of MPXJ's MPP14 reader;
- Project's XML format (MSPDI);
- MPX.

## Licence

MPXJ (https://github.com/joniles/mpxj, Jon Iles and contributors) is
licensed under the GNU Lesser General Public License 2.1, and this port is a
derivative of it, so this whole module is under the LGPL 2.1 or later: see
`LICENSE`. The page loads it as a separate file
(`/vendor/local/mpxj@1/mpxj.mjs`), so it can be rebuilt from this source and
replaced.

## What comes from MPXJ

Ported from MPXJ at commit `3f9244a9c49b052300c2500545cb5ea65340792b`
(6 Oct 2026):

| Here | MPXJ |
| --- | --- |
| `src/blocks.ts` | `mpp/Props14`, `FixedMeta`, `FixedData`, `VarMeta12`, `Var2Data` |
| `src/bytes.ts` | `common/ByteArrayHelper`, `mpp/MPPUtility` |
| `src/fieldmap.ts` | `mpp/FieldMap`, `FieldMap14`, `common/FieldTypeHelper` |
| `src/fields.ts` | generated by `tools/gen_fields.py` from `TaskField`, `ResourceField`, `AssignmentField` and `common/MPP*Field` |
| `src/mpp14.ts` | `mpp/MPPReader`, `MPP14Reader`, `ConstraintFactory`, `ResourceAssignmentFactory`, `ProjectPropertiesReader`, `CompObj` |
| `src/mpx.ts` | record and field numbers from `mpx/MPXReader`, `MPXTaskField`, `MPXResourceField` |

Written for this module: `src/cfb.ts` (OLE compound files, from
Microsoft's [MS-CFB] specification), `src/mspdi.ts` and `src/xml.ts` (from
Microsoft's published MSPDI schema), `src/rtf.ts`, `src/model.ts`,
`src/index.ts`.

Not read: timephased data, calendars, views, filters, groups, custom-field
value lists and enterprise custom fields; Project 2007 and older `.mpp`
files.

## Building

```
python tools/gen_fields.py <path to an MPXJ checkout>   # only when updating MPXJ
node build.mjs                                          # writes vendor/local/mpxj@1/mpxj.mjs
```

`build.mjs` uses esbuild from the site's `frontend/node_modules`.