geoman-io/leaflet-geoman

Document Typescript casting of event payload

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#1,014 opened on Oct 19, 2021

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good first issuehelp wantedimprovementtypescript

Description

In the event payload the return type of layer is `L.Layer? so it needs to be casted to the Layer-Type.

layer.on('pm:edit', (e) => {
  if(e.shape === 'Polygon'){
     (e.layer as Polygon).getLatLngs();
  }
});

I think following should work too: (But not tested)

layer.on('pm:edit', (e) => {
  if(e.layer instanceof L.Polygon){
     (e.layer as Polygon).getLatLngs();
  }
});

This should documented in the Readme

Explainations:

Contributor guide

Tech stack
typescript
Domain
documentation
Issue type
documentation
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
under 1 hour
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
TypeScript basicsleaflet geoman event system
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
80
Research direction
Add a section in the README.md file explaining how to cast the event payload's layer type to a specific type like Polygon. Use the code examples provided in the issue (e.g., `(e.layer as Polygon).getLatLngs()`) and reference the StackOverflow link and issue #945 for additional context. Ensure the documentation covers both the inline cast and the instanceof check approach.