JavaScript recursion: Maximum call stack size exceeded

Question

I have a recursive function for moving some circles on a canvas. Overed circle is enlarged (zoom in) and all the other circles is pushed away. Pushed circles push other circles

Answer 1

Try to make sure the recursion step is only done for greater than base case. For example in quicksort here:

function qsort(k){

if(k == []){
    return k;
}
if(k.length == 1){
    return k;
}

//pick random pivot

var p = Math.floor(Math.random()*k.length);
console.log("pivot is" +  p + "\n");

//set left and right iter

var l = 0; var r = k.length - 1;

while( l < r){
console.log('hi\n');
//move l until its element is bigger than pivot

while(k[l] < k[p] && l < k.length) {
    l++;
    console.log('h1i\n');

}

//move r until its element is smaller than pivot

while(k[r] > k[p] && r >= 0) {r--;

    console.log('h2i\n');
}

//swap k[l] with k[r]

var temp = k[l]; k[l] = k[r]; k[r] = temp;
}

if(l == r){
//swap k[l] with k[p]

temp = k[l]; k[l] = k[p]; k[p] = temp;

}



var lk = k.slice(0,p); var rk = k.slice(p,k.length);

console.log(lk);
console.log(rk);

if(lk.length > 1){
 lk = qsort(lk);
}
if(rk.length > 1){
 rk = qsort(rk);
}

result = lk.concat(rk);

console.log(result);

return result;

}

var k = [23,245,67,34,24];
var result = qsort(k);
console.log(result);
//document.write(result);

If instead of lk.length > 1 you used something like lk != [] or not have a check, it could sometimes give call stack size exceeded errors and sometimes work depending on which pivots got chosen.