JSFiddle - React, Tailwind, and code Playground

by jfriend00

CSS

body {font-family: "Courier New"; font-size: 12px;}

JavaScript

var a = [];
a[0] = 31;
a[1] = 12; 
a[2] = 666; 
a[7] = 4; 
a[8] = 053;


// sortFn is optional array sort callback function, 
// defaults to numeric sort if not passed
function sortSparseArray(arr, sortFn) {
    var tempArr = [], indexes = [];
    for (var i = 0; i < arr.length; i++) {
        // find all array elements that are not undefined
        if (arr[i] !== undefined) {
            tempArr.push(arr[i]);    // save value
            indexes.push(i);         // save index
        }
    }
    // sort values (numeric sort by default)
    if (!sortFn) {
        sortFn = function(a,b) {
            return(a - b);
        }
    }
    tempArr.sort(sortFn);
    // put sorted values back into the indexes in the original array that were used
    for (var i = 0; i < indexes.length; i++) {
        arr[indexes[i]] = tempArr[i];
    }
    return(arr);
}

var output = JSON.stringify(sortSparseArray(a)).replace(/null/g, "undefined");
document.body.innerHTML = output;

a = [];
a[0] = "hello";
a[1] = "GoodBye"; 
a[2] = "whatever"; 
a[7] = "Fun"; 
a[8] = "Waterslide";
output = JSON.stringify(sortSparseArray(a, function(a, b) {
    return a.toLowerCase().localeCompare(b.toLowerCase())
})).replace(/null/g, "undefined");
document.body.innerHTML += "<br>" + output;