JavaScript Object converting and sorting

I have an object function that turns my array into an object with a key and value.

function toObject(arr) {
    var obj = {};
    for (var i = 0; i < arr.length; ++i) {
        var remaining = arr.length - i;
        if (arr[i] !== undefined) {
            if (remaining == arr.length) {
                obj['min'] = arr[i];
            }
            else if (remaining === 1) {
                obj['max'] = arr[i];
            }
            else {
                obj[(i*10).toString()] = arr[i];
            }
        }
    }
    return obj;
}
// { 10: "2", 20: "3", 30: "4", min: "1", max: "5" }

How can I sort min to be first in the object and max to be last in the object, convert the key value to a string, and the value to a number: {'min':1, '10%':2, '20%':3, '30%':4, 'max': 5}

My attempt:

function toObject(arr) {
    var obj = {};
    for (var i = 0; i < arr.length; ++i) {
        var remaining = arr.length - i;
        if (arr[i] !== undefined) {
            if (remaining == arr.length) {
                obj["'min'"] = arr[Number(i)];
            }
            else if (remaining === 1) {
                obj["'max'"] = arr[Number(i)];
            }
            else {
                obj["'" + (i*10).toString() + "%'"] = arr[Number(i)];
            }
        }
    }
    return obj;
}