Испытание: Рекорды по прыжкам в длину

var qualificationDistance = 200;
var attempts = [120, 150, 160, 201, 203, 180, 202];
var qualified;
var averageBest;

for (var i = 0; i <= attempts.length-2; i++){
var longestJump = attempts[i]; //longestJump = 120
for (var j = i + 1; j <= attempts.length - 1; j++){
if(longestJump < attempts[j]){
var swap = attempts[i]; //swap = 120
longestJump = attempts[j]; //longestJump = 150
attempts[i] = longestJump; //attempts[i] = 150
attempts[j] = swap;//attempts[j] = 120
}
}
}

console.log(attempts)
var averageBest = (attempts[0] + attempts[1] + attempts[2]) / 3;
console.log(averageBest)
if((attempts[0] + attempts[1] + attempts[2]) / 3 > 200 ){
qualified = true}else{
qualified = false}

Поясните, пожалуйста, почему, если в строке " var swap = attempts[i] " attempts[i] заменить на longestJump, получается ошибка? Не до конца понимаю этот момент:(