Infdig in Custom groupBy - angularjs

Question

i recently needed some kinda customized repeater, which group data by their key, but not simply group them all together, so i read several references and things,... and at last i come up to copy
groupBy from this article which he seem to complete it at best, ...
http://sobrepere.com/blog/2014/10/14/creating-groupby-filter-angularjs/
And then i customized so it become like this:
the things my group by do... is:
Group Data Together Until It Reach Differences.
but the matter is that though it work, it still generate infdig, i know it's because the digest done call other one, but what i don't know is how to solve it in very easy and understandable manner, as i'm new to JavaScript...
app.filter('groupBy', function () {
var results = {};
return function (data, key) { //Data => My Objects Array - Key => Name Of Filtered Property
if (!(data && key)) return;
var result;
if (!this.$id) {
result = {};
} else {
var scopeId = this.$id;
if (!results[scopeId]) {
results[scopeId] = {};
this.$on("$destroy", function () {
delete results[scopeId];
});
}
result = results[scopeId];
}
for (var groupKey in result)
result[groupKey].splice(0, result[groupKey].length);
var grpKey = -1; //GroupKey
var lastUserId;
for (var i = 0; i < data.length; i++) {
if (!result[grpKey] || lastUserId && lastUserId != data[i][key]) // Ex.: result[data[0]["UserId"]]{ => return UserId
result[++ grpKey] = [];
result[grpKey].push(data[i]);
lastUserId = data[i][key];
}
var keys = Object.keys(result);
for (var k = 0; k < keys.length; k++) {
if (result[keys[k]].length === 0)
delete result[keys[k]];
}
return result;
};
});

Answer 1

In this url is working perfectly...
http://plnkr.co/edit/8jB4wSRtKfVmEsTGZtfV?p=preview
app.filter('groupBy', function ($timeout) {
return function (data, key) {
if (!key) return data;
var outputPropertyName = '__groupBy__' + key;
if(!data[outputPropertyName]){
var result = {};
for (var i=0;i<data.length;i++) {
if (!result[data[i][key]])
result[data[i][key]]=[];
result[data[i][key]].push(data[i]);
}
Object.defineProperty(result, 'length', {enumerable: false, value: Object.keys(result).length});
Object.defineProperty(data, outputPropertyName, {enumerable:false, configurable:true, writable: false, value:result});
$timeout(function(){delete data[outputPropertyName];},0,false);
}
return data[outputPropertyName];
};
});