I am using underscoreJS to manage a list of wrestler objects, they have a championship object attached that has details or is set to false.
Please take a look at this code snippet: http://jsfiddle.net/JpPjA/
var wrestlers = [{"id":60,"alias":"Natalya Hart","male":true,"championship":false,"alias_url":"natalya-hart"},{"id":59,"alias":"Naomi","male":true,"championship":false,"alias_url":"naomi"},{"id":58,"alias":"Layla","male":true,"championship":false,"alias_url":"layla"},{"id":4,"alias":"The Rock","male":true,"championship":{"id":3,"image":"wwe-championship.png","title":"WWE Championship"},"alias_url":"the-rock"},
{"id":3,"alias":"Antonio Cesaro","male":true,"championship":{"id":5,"image":"wwe-united-states-championship.png","title":"WWE United States Championship"},"alias_url":"antonio-cesaro"},{"id":2,"alias":"Wade Barrett","male":true,"championship":{"id":4,"image":"wwe-intercontinental-championship.png","title":"WWE Intercontinental Championship"},"alias_url":"wade-barrett"},
{"id":1,"alias":"Alberto Del Rio","male":true,"championship":{"id":2,"image":"world-heavyweight-championship.png","title":"World Heavyweight Championship"},"alias_url":"alberto-del-rio"}];
var g = _.groupBy(wrestlers, 'championship');
console.log(JSON.stringify(g));
Unfortunately it outputs it as an array with two key names: "false" and "[object Object]"
Is there a way to give the output predefined key names? [object Object] as a key name bothers me more.