Does anyone know why this is infinite loop?-CodePudding

var arr = [1,2,3,4,5]
for (var i = 2; i < arr.length; i  ) {

    [arr[i], arr[i 1]] = [arr[i 1], arr[i]]
    
}

console.log(arr);

I have no idea why this is an infinite loop..

CodePudding user response：

Executing this will give you a sense of what happens.

async function inifiniteLoop() {
  var arr = [1, 2, 3, 4, 5];
  for (var i = 2; i < arr.length; i  ) {
    [arr[i], arr[i   1]] = [arr[i   1], arr[i]];
    console.log(arr);
    console.log(`i: ${i}; arr.length: ${arr.length}`);
    await sleep(2000);
  }
}

function sleep(ms) {
  return new Promise((resolve) => setTimeout(resolve, ms));
}

(async () => await inifiniteLoop())();

While you would get an IndexOutOfBounds exception in Java and many other languages this works in JavaScript.

const array = [34]
console.log(array)
array[3] = 23
console.log(array)