javascript - Leaflet toggle buttons only work on the first click -

i have button want use toggle map layer on , off. click once , layer adds map, click again , goes away (and on). right button works on first click , none thereafter.

i think has fact it's written if/else statement. condition satisfied, function ends, , that's end of it.

looking guidance... how modify code make functional toggle button?

my button:

<button id="buttona" onclick=="onoff();">button a</button> 

then, within function $.getjson("mydata.json", function(data) {...}); have following:

function onoff(){   currentvalue = document.getelementbyid('onoff').value; }      document.getelementbyid("buttona").addeventlistener("click", function(){     if (currentvalue = "off"){        layera.addto(map);        document.getelementbyid("onoff").value="on";      }      else{        map.removelayer(layera);         document.getelementbyid("onoff").value="off";     } }); 

change if (currentvalue = "off") if (currentvalue == "off")

edited: try in way:

button:

<button id="buttona" onclick="onoff();">button a</button> 

and js:

function onoff(){       currentvalue = document.getelementbyid('onoff').value;        if (currentvalue == "off"){         layera.addto(map);         document.getelementbyid("onoff").value="on";       }       else{         map.removelayer(layera);          document.getelementbyid("onoff").value="off";       }     }