[JS] extract the scores in the string, calculate the average score after summarizing, compare with each score, and output

// chestnuts ： Extract the fraction in the string , Calculate the average score after summarizing , And compare with each score , Output 
var s=" Zhang San  56 branch , Li Si 74 branch , Wang Wu 92 branch , Zhao Liu 84 branch ";
var a=s.match(/\d+/g),sum=0;// Extract numbers 
for (var i = 0; i < a.length; i++) {
    sum+=parseFloat(a[i]);
}
var avg=sum/a.length;
function f() {
    var n=parseFloat(arguments[1]);
    return n+" branch "+"("+((n>avg)?(" Above average "+(n-avg)):(" Below average "+(avg-n)))+" branch )";
}
var s1=s.replace(/(\d+) branch /g,f);
console.log(s1);