button needs to be clicked twice to toggle layer visibility? - button

Question

Using an example I found on this thread https://gis.stackexchange.com/questions/198896/mapbox-gljs-group-layers/198920#198920?newreg=120a87a082494e41b2e6ab240c94b266 I have grouped multiple layers together and created a single toggle button to turn on and off visibility.
However, the buttons need to be clicked twice to trigger the function. Is it possible to have them only clicked once for the function to work?
Here is my codepen example https://codepen.io/charlie-enright/pen/BarRgbo
//whatever layers you want to toggle go in to this function
toggleLayer(['site location markers'], 'markers');
toggleLayer(['Pen Dinas', 'Rudbaxton','Brawdy Castle', 'Caer Blaen Minog', 'Castell Bach', 'Castell Gwyn', 'Tancredston', 'Thornton Rath', 'Walesland Rath'], 'Geophys');
toggleLayer(['Pendinas 50cm DSM'], '50cm DSM');
toggleLayer(['Pendinas 50cm DTM'], '50cm DTM');
function toggleLayer(ids, name) {
var link = document.createElement('a');
link.href = '#';
link.className = 'active';
link.textContent = name;
link.onclick = function (e) {
e.preventDefault();
e.stopPropagation();
for (layers in ids){
var visibility = map.getLayoutProperty(ids[layers], 'visibility');
if (visibility === 'visible') {
map.setLayoutProperty(ids[layers], 'visibility', 'none');
this.className = '';
} else {
this.className = 'active';
map.setLayoutProperty(ids[layers], 'visibility', 'visible');
}
}
};
var layers = document.getElementById('menu');
layers.appendChild(link);
}

Answer 1

I'm not exactly sure why, but the first time you check the visibility of the layer var visibility = map.getLayoutProperty(ids[layers], 'visibility');, visibility is undefined.
If you check for this in the if statement below, it will toggle on the first click:
if (visibility === 'visible' || visibility === undefined) {
// ^^ if 'visible' or undefined, set visibility to 'none'
...
}