Sort array of objects by single key with date value

Question

I have an array of objects with several key value pairs, and I need to sort them based on \'updated_at\':

[
    {
        \"updated_at\" : \"2012-01-01T06:25         


        

Answer 1

Sorting by an ISO formatted date can be expensive, unless you limit the clients to the latest and best browsers, which can create the correct timestamp by Date-parsing the string.

If you are sure of your input, and you know it will always be yyyy-mm-ddThh:mm:ss and GMT (Z) you can extract the digits from each member and compare them like integers

array.sort(function(a,b){
    return a.updated_at.replace(/\D+/g,'')-b.updated_at.replace(/\D+/g,'');
});

If the date could be formatted differently, you may need to add something for iso challenged folks:

Date.fromISO: function(s){
    var day, tz,
    rx=/^(\d{4}\-\d\d\-\d\d([tT ][\d:\.]*)?)([zZ]|([+\-])(\d\d):(\d\d))?$/,
    p= rx.exec(s) || [];
    if(p[1]){
        day= p[1].split(/\D/).map(function(itm){
            return parseInt(itm, 10) || 0;
        });
        day[1]-= 1;
        day= new Date(Date.UTC.apply(Date, day));
        if(!day.getDate()) return NaN;
        if(p[5]){
            tz= (parseInt(p[5], 10)*60);
            if(p[6]) tz+= parseInt(p[6], 10);
            if(p[4]== '+') tz*= -1;
            if(tz) day.setUTCMinutes(day.getUTCMinutes()+ tz);
        }
        return day;
    }
    return NaN;
}
if(!Array.prototype.map){
    Array.prototype.map= function(fun, scope){
        var T= this, L= T.length, A= Array(L), i= 0;
        if(typeof fun== 'function'){
            while(i< L){
                if(i in T){
                    A[i]= fun.call(scope, T[i], i, T);
                }
                ++i;
            }
            return A;
        }
    }
}
}