JSFiddle - React, Tailwind, and code Playground

HTML

<textarea rows="10" cols="50" id="log"></textarea>

JavaScript

var arr=["2 xxx","20 axxx","38 xxxx","20 bx","8540 xxxxxx"];
arr.sort(function(a,b){
    a=a.split(" ");
    b=b.split(" ");
    var an=parseInt(a[0],10);
    var bn=parseInt(b[0],10);
    return an<bn?1:(an>bn?-1:(a[1]<b[1]?-1:(a[1]>b[1]?1:0)));
});
document.getElementById("log").value=arr.join("\n");