Question

I came across the following script, and do not understand the first line. It apparently either returns JSON.stringify or an anonymous function. Is it best to do it this way, or using the traditional the function printObj(obj)? Also, where does JSON get defined? Thanks

var printObj = typeof JSON != "undefined" ? JSON.stringify : function(obj) {
  var arr = [];
  $.each(obj, function(key, val) {
    var next = key + ": ";
    next += $.isPlainObject(val) ? printObj(val) : val;
    arr.push( next );
  });
  return "{ " +  arr.join(", ") + " }";
};

$("#log").append( printObj(object1) );

Answer 1

var printObj = // setting the variable printObj
               typeof JSON != 'undefined' // if this is true then set printObj to
                    ? JSON.stringify // <- ...this function
               : function( obj ) {
                   // otherwise let's build it ourselves...
               };

typeof JSON != 'undefined' will return true or false whether the identifier JSON has been defined. typeof x will not cause a reference error if x has not been defined.