The letter L has not been defined in this particular instance (Leaflet.js node package)

I have been attempting to utilize the example provided in the Leaflet quickstart guide within Angular 7. However, I keep encountering the error message 

ERROR ReferenceError: L is not defined
. It is worth noting that I have not included Leaflet via JS files, but rather installed it through npm using the command npm install leaflet. I can confirm that it is present in my node_modules directory.

import { Component, OnInit } from '@angular/core';
declare let L;


@Component({
  selector: 'app-mapvisual',
  templateUrl: './mapvisual.component.html',
  styleUrls: ['./mapvisual.component.css']
})
export class MapvisualComponent implements OnInit {

  constructor() { }

  ngOnInit() {
    const map = L.map('map').setView([51.505, -0.09], 13);

    L.tileLayer('https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png', {
      attribution: '© <a href="https://www.openstreetmap.org    /copyright">OpenStreetMap</a> contributors'
    }).addTo(map);
  }
}

EDIT: I managed to find the solution by following the instructions provided here.

angulartypescriptleaflet

Answer №1

Ensure these necessary resources are included in your index.html


<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8>
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>

    <link rel="stylesheet" href="https://unpkg.com/<a href="/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="741811151218110034455a415a45">[email protected]</a>/dist/leaflet.css"
    integrity="sha512-xwE/Az9zrjBIphAcBb3F6JVqxf46+CDLwfLMHloNu6KEQCAWi6HcDUbeOfBIptF7tcCzusKFjFw2yuvEpDL9wQ=="
    crossorigin=""/>

    <!-- Make sure you put this AFTER Leaflet's CSS -->
    <script src="https://unpkg.com/<a href="/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="234f4642454f465763120d160d12">[email protected]</a>/dist/leaflet.js"
    integrity="sha512-GffPMF3RvMeYyc1LWMHtK8EbPv0iNZ8/oTtHPx9/cc2ILxQ+u905qIwdpULaqDkyBKgOaB57QTMg7ztg8Jm2Og=="
    crossorigin=""></script>
</head>
<body>

</body>
</html>

Insert the following code into your component.html file

 <div id="mapid"></div>

Utilize the component.css file

#mapid { height: 180px; }

Implement the code in your component.ts file

import { Component, OnInit } from '@angular/core';
declare let L;


@Component({
  selector: 'app-mapvisual',
  templateUrl: './mapvisual.component.html',
  styleUrls: ['./mapvisual.component.css']
})
export class MapvisualComponent implements OnInit {

  constructor() { }

  ngOnInit() {
    const map = L.map('mapid').setView([51.505, -0.09], 13);

    L.tileLayer('https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png', {
      attribution: '© <a href="https://www.openstreetmap.org    /copyright">OpenStreetMap</a> contributors'
    }).addTo(map);
  }
}

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