to run this file "node script.js" make sure you have node installed in your environment,I have statically assigned the array change it as per the test cases

script.js

var array = [{
  name:'xyz',
  ranking: 13
},{
  name:'xys',
  ranking:243
},{
  name:'pqr',
  ranking: -32
},{
  name:'abc',
  ranking: 0
}]

function sortByRank(arr){
for(let i=0;i<arr.length-1;i++){
  if(arr[i].ranking>arr[i+1].ranking){
    var temp = arr[i];
    arr[i] = arr[i+1];
    arr[i+1]=temp;
  }
}
return arr;
}

function avgRanking(arr){
	let sum=0;
	for (var i = 0; i < arr.length; i++) {
		sum+=arr[i].ranking;
	}
	return sum/arr.length;
}
let avg = avgRanking(array);
console.log("average ranking is " + avg);
let sortedarr = sortByRank(array);
for(let i=0;i<sortedarr.length;i++){
	console.log(sortedarr[i].ranking);	
	// document.write(sortedarr[i].ranking);
}