Could someone explain me how this code works line to line? Thanks.

Question

How many elements will be pushed to the array res?

var str='I love JS!',
j=0,
res=[];
while ((j=str.indexOf(",j+1))>0){
res.push(j+1);
}

Answer 1

The answer in the js challenge is two,your question is wrong,since its been a long while i challenged, i need the correct question to explain this