JSFiddle - React, Tailwind, and code Playground

HTML

<div id="r"></div>

JavaScript

var a1 =["A1", "A10", "A11", "A12", "A2", "A3", "A4", "B10", "B2", "F1", "F12", "F3"];

var a2 = a1.sort(function(a,b){
    var charPart = [a.substring(0,1), b.substring(0,1)],
        numPart = [a.substring(1)*1, b.substring(1)*1];
    debugger;
    if(charPart[0] < charPart[1]) return -1;
    else if(charPart[0] > charPart[1]) return 1;
    else{ //(charPart[0] == charPart[1]){
        if(numPart[0] < numPart[1]) return -1;
        else if(numPart[0] > numPart[1]) return 1;
    }
});

$('#r').html(a2.toString())