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Leaflet verwendet eine Variable für addTo(map)

BillChappell

OK, ich habe eine einfache Krebs-Webkarte in Leaflet und stecke bei einem Problem fest.<\/P>

1. Ich habe ein HTML-Kontrollkästchen, das beim Anklicken eine Ebene einschaltet. (Layer switcher ist keine Option) Dies ruft im Grunde eine Funktion auf und übergibt den Namen der Krebsebene, z.B. updateLayerVis("lung")<\/P>

<\/P>

2. Ich habe verschiedene Krebsarten nach Namen definiert, z.B. var throat = new L.GeoJSON(data .....<\/P>

<\/P>

3. Die oben genannte Funktion übergibt den Wert 'lung' an 'a' unten. Es scheint, als würde ein einfacher String namens 'lung' übergeben, während addTo eine Ebene erwartet. Ist es möglich, diesen String zu verwenden, um die entsprechende Ebene zur Karte hinzuzufügen?<\/P>

<\/P>

function updateLayerVis(a){<\/P>

console.log(a); \/\/ lung<\/P>

a.value.addTo(map); \/\/ gibt einen Fehler zurück "a.addTo ist keine Funktion"<\/P>

a.addTo(map); \/\/ gibt einen Fehler zurück "a.addTo ist keine Funktion"<\/P>

lung.addTo(map); \/\/ funktioniert, aber mit 15 Kontrollkästchen bräuchte ich eine große switch-Funktion.<\/P>

};<\/P>

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Esri Leaflet

Accepted answers

FC_Basson

Instead of creating a variable with the name of each data layer, rather create a list of layers with the layer name as an index e.g.

<SPAN class="keyword token">var</SPAN> maplayers <SPAN class="operator token">=</SPAN> <SPAN class="punctuation token">[</SPAN><SPAN class="punctuation token">]</SPAN><SPAN class="punctuation token">;</SPAN>
maplayers<SPAN class="punctuation token">[</SPAN><SPAN class="string token">"lung"</SPAN><SPAN class="punctuation token">]</SPAN> <SPAN class="operator token">=</SPAN> <SPAN class="keyword token">new</SPAN> <SPAN class="token class-name">L<SPAN class="punctuation token">.</SPAN>GeoJSON</SPAN><SPAN class="punctuation token">(</SPAN>data<SPAN class="punctuation token">.</SPAN><SPAN class="punctuation token">.</SPAN><SPAN class="punctuation token">.</SPAN>
maplayers<SPAN class="punctuation token">[</SPAN><SPAN class="string token">"throat"</SPAN><SPAN class="punctuation token">]</SPAN> <SPAN class="operator token">=</SPAN> <SPAN class="keyword token">new</SPAN> <SPAN class="token class-name">L<SPAN class="punctuation token">.</SPAN>GeoJSON</SPAN><SPAN class="punctuation token">(</SPAN>data<SPAN class="punctuation token">.</SPAN><SPAN class="punctuation token">.</SPAN><SPAN class="punctuation token">.</SPAN><SPAN class="line-numbers-rows"><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN></SPAN>

Then when clicking on the checkbox you can use the string value to activate the indexed layer.

<SPAN class="keyword token">function</SPAN> <SPAN class="token function">updateLayerVis</SPAN><SPAN class="punctuation token">(</SPAN>a<SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">{</SPAN>
&nbsp;&nbsp; <SPAN class="keyword token">var</SPAN> lyr <SPAN class="operator token">=</SPAN> maplayers<SPAN class="punctuation token">[</SPAN>a<SPAN class="punctuation token">]</SPAN><SPAN class="punctuation token">;</SPAN>
&nbsp;&nbsp; lyr<SPAN class="punctuation token">.</SPAN><SPAN class="token function">addTo</SPAN><SPAN class="punctuation token">(</SPAN>map<SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN>
<SPAN class="punctuation token">}</SPAN>‍‍‍<SPAN class="line-numbers-rows"><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN></SPAN>

All comments

FC_Basson

Yes, applying the addTo function directly to the indexed layer item should also work. It's just nice to have the item available as a short variable if you need to refer to it further down in the function again.

BillChappell

I was going toward this route when I saw your answer. It was cleaner then mine so I tried it. I also tried mapLayers.addTo(map); and this worked.

FC_Basson

Instead of creating a variable with the name of each data layer, rather create a list of layers with the layer name as an index e.g.

<SPAN class="keyword token">var</SPAN> maplayers <SPAN class="operator token">=</SPAN> <SPAN class="punctuation token">[</SPAN><SPAN class="punctuation token">]</SPAN><SPAN class="punctuation token">;</SPAN>
maplayers<SPAN class="punctuation token">[</SPAN><SPAN class="string token">"lung"</SPAN><SPAN class="punctuation token">]</SPAN> <SPAN class="operator token">=</SPAN> <SPAN class="keyword token">new</SPAN> <SPAN class="token class-name">L<SPAN class="punctuation token">.</SPAN>GeoJSON</SPAN><SPAN class="punctuation token">(</SPAN>data<SPAN class="punctuation token">.</SPAN><SPAN class="punctuation token">.</SPAN><SPAN class="punctuation token">.</SPAN>
maplayers<SPAN class="punctuation token">[</SPAN><SPAN class="string token">"throat"</SPAN><SPAN class="punctuation token">]</SPAN> <SPAN class="operator token">=</SPAN> <SPAN class="keyword token">new</SPAN> <SPAN class="token class-name">L<SPAN class="punctuation token">.</SPAN>GeoJSON</SPAN><SPAN class="punctuation token">(</SPAN>data<SPAN class="punctuation token">.</SPAN><SPAN class="punctuation token">.</SPAN><SPAN class="punctuation token">.</SPAN><SPAN class="line-numbers-rows"><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN></SPAN>

Then when clicking on the checkbox you can use the string value to activate the indexed layer.

<SPAN class="keyword token">function</SPAN> <SPAN class="token function">updateLayerVis</SPAN><SPAN class="punctuation token">(</SPAN>a<SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">{</SPAN>
&nbsp;&nbsp; <SPAN class="keyword token">var</SPAN> lyr <SPAN class="operator token">=</SPAN> maplayers<SPAN class="punctuation token">[</SPAN>a<SPAN class="punctuation token">]</SPAN><SPAN class="punctuation token">;</SPAN>
&nbsp;&nbsp; lyr<SPAN class="punctuation token">.</SPAN><SPAN class="token function">addTo</SPAN><SPAN class="punctuation token">(</SPAN>map<SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN>
<SPAN class="punctuation token">}</SPAN>‍‍‍<SPAN class="line-numbers-rows"><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN></SPAN>

JohnGravois

check out this stack overflow thread.

http://stackoverflow.com/questions/5613834/convert-string-to-variable-name-in-javascript

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