var string="start,stop,speed,start,speed,start,relocicty,start,start,start,start";
var count=1;
for (let index = 0; index < string.length; index++) {
    var a=string.indexOf("start",index);
    // console.log(a);
    if(a!=-1&&string.indexOf("start",index)!=string.indexOf("start",index-1)){
        count++;
         }
     }
console.log(count);