Develop Reference

Function returning object instead of Array, unable to .Map

I'm parsing an order feed to identify duplicate items bought and group them with a quantity for upload. However, when I try to map the resulting array, it's showing [object Object], which makes me think something's converting the return into an object rather than an array.
The function is as follows:
function compressedOrder (original) {
var compressed = [];
// make a copy of the input array
// first loop goes over every element
for (var i = 0; i < original.length; i++) {
var myCount = 1;
var a = new Object();
// loop over every element in the copy and see if it's the same
for (var w = i+1; w < original.length; w++) {
if (original[w] && original[i]) {
if (original[i].sku == original[w].sku) {
// increase amount of times duplicate is found
myCount++;
delete original[w];
}
}
}
if (original[i]) {
a.sku = original[i].sku;
a.price = original[i].price;
a.qtty = myCount;
compressed.push(a);
}
}
return compressed;
}
And the JS code calling that function is:
contents: compressedOrder(item.lineItems).map(indiv => ({
"id": indiv.sku,
"price": indiv.price,
"quantity": indiv.qtty
}))
The result is:
contents: [ [Object], [Object], [Object], [Object] ]
When I JSON.stringify() the output, I can see that it's pulling the correct info from the function, but I can't figure out how to get the calling function to pull it as an array that can then be mapped rather than as an object.
The correct output, which sits within a much larger feed that gets uploaded, should look like this:
contents:
[{"id":"sku1","price":17.50,"quantity":2},{"id":"sku2","price":27.30,"quantity":3}]
{It's probably something dead simple and obvious, but I've been breaking my head over this (much larger) programme till 4am this morning, so my head's probably not in the right place}

Turns out the code was correct all along, but I was running into a limitation of the console itself. I was able to verify this by simply working with the hard-coded values, and then querying the nested array separately.
Thanks anyway for your help and input everyone.

contents: compressedOrder(item.lineItems).map(indiv => ({
"id": indiv.sku,
"price": indiv.price,
"quantity": indiv.qtty
}))
In the code above the compressedOrder fucntion returns an array of objects where each object has sku, price and qtty attribute.
Further you are using a map on this array and returning an object again which has attributes id, price and quantity.
What do you expect from this.

Not sure what exactly solution you need but I've read your question and the comments, It looks like you need array of arrays as response.
So If I've understood your requirement correctly and you could use lodash then following piece of code might help you:
const _ = require('lodash');
const resp = [{key1:"value1"}, {key2:"value2"}].map(t => _.pairs(t));
console.log(resp);
P.S. It is assumed that compressedOrder response looks like array of objects.

JavaScript - Find objects by similar property and push it in a new array

I have the following JSON tree:
[
{
"category":"PASTAS",
"createdAt":"2016-01-01T19:47:57.813Z",
"currency":"$",
"dishName":"Spaghetti",
"estTime":"10-20 min",
"price":10,
"subName":"Pasta",
"updatedAt":"2016-04-28T20:48:06.800Z"
},
{
"category":"PIZZAS",
"createdAt":"2016-04-19T21:44:56.285Z",
"currency":"$",
"dishName":"Ai Funghi Pizza ",
"estTime":"20-30 min",
"price":20,
"subName":"Pizza",
"updatedAt":"2016-04-28T20:58:39.499Z"
},
{
"category":"PIZZAS",
"createdAt":"2016-04-19T21:44:56.285Z",
"currency":"$",
"dishName":"Seafood Pizza",
"estTime":"20-30 min",
"price":10,
"subName":"Pizza",
"updatedAt":"2016-04-28T20:58:39.499Z"
}
]
As you can see in the JSON tree the element category:"PIZZAS" repeats two times, what I would like to do is to either create a new array or organize these results in a way to avoid repetition in all the other duplicates, i.e. in the example above, I would have a final results like this:
Pastas:
Spaghetti
Pizza:
Ai Fungi Pizza,
Seafood Pizza
Any ideas on how to achieve the wanted result?

Assuming the array is named data, this should do the trick:
var result = {}; // Create an output object.
for(var i = 0; i < data.length; i++){ // Loop over the input array.
var row = data[i]; // Store the current row for convenience.
result[row.category] = result[row.category] || []; // Make sure the current category exists on the output.
result[row.category].push(row.dishName); // Add the current dish to the output.
}

lodash#groupBy is exactly what you want.
lodash.groupBy(foods, function(food) { return food.category; });
Here's an example with your JSON:
http://codepen.io/damongant/pen/xVQBXG

Looping through nesting of objects and arrays with Javascript and underscore

I am trying to access objects that are nested within an array. I start with this JSON object (which was derived from an XML database output):
{"report":
{"date":"15 Apr 2016",
"metrics":
{"metric":
[
{"name":"Bank Angle",
"display_parent_group":"Bankfull",
"display_child_group":"SiteShape",
"tolerance":"0.05",
"visits":
{"visit":
[
{"visit_id":"3047","value": "0.47"},
{"visit_id":"2164","value": "0.55"},
{"visit_id":"1568","value": "0.72"},
{"visit_id":"3431","value": "0.12"},
{"visit_id":"2428","value": "0.44"},
{"visit_id":"1567","value": "0.49"}
]}},
{"name":"Bank Angle SD",
"display_parent_group":"Bankfull",
"display_child_group":"SiteShape",
"tolerance":"0.05",
"visits":
{"visit":
[
{"visit_id":"3047","value": "0.12"},
{"visit_id":"2164","value": "0.05"},
{"visit_id":"1568","value": "0.21"},
{"visit_id":"3431","value": "0.68"},
{"visit_id":"2428","value": "0.22"},
{"visit_id":"1567","value": "0.13"}
]}},
{"name":"Bankfull Area",
"display_parent_group":"Bankfull",
"display_child_group":"SiteSize","tolerance":"0.05",
"visits":
{"visit":
[
{"visit_id":"3047","value": "202"},
{"visit_id":"2164","value": "193"},
{"visit_id":"1568","value": "115"},
{"visit_id":"3431","value": "258"},
{"visit_id":"2428","value": "89"},
{"visit_id":"1567","value": "206"}
]}}
]
}
}
}
I then use underscore to extract a subset of metric objects:
var table_metric = JSONData.report.metrics.metric;
var target_metrics = _.where(table_metric, {
display_parent_group : 'Bankfull', display_child_group: 'SiteShape'
});
This results in an array with two nested objects. Where I'm having a problem is then accessing the array of objects which is nested inside visits.visit. If, for instance, I want to build an array of values associated with the key visit_id, and I try:
function buildVisitIDArray(target_metrics) {
var attrList = [];
for(var i=0; i<target_metrics.length; i++) {
var visit_records = target_metrics[i].visits[1];
console.log(visit_records);
for(visit_record in visit_records) {
attrList.push(_.pluck(visit_record, "visit_id"));
}
}
return attrList
}
I just get an array of undefined results. I've spent hours trying variations on the syntax to get at the nested "visit" objects, but I just can't seem to figure it out.
Any help is much appreciated for this novice!

In your buildVisitIDArray function, you are trying to get target_metrics[i].visits[1] as if it was an array, but it's actually an object, so you should use it this way:
function buildVisitIDArray(target_metrics) {
attrList = [];
for(var i=0; i<target_metrics.length; i++) {
var visit_records = target_metrics[i].visits; // Removed the array call ([1])
console.log(visit_records);
for(visit_record in visit_records) {
attrList.push(_.pluck(visit_records[visit_record], "visit_id"));
}
}
return attrList;
}
Hope it helps :)

You may also have an issue if you're not defining attrList with the var keyword somewhere else in your code.
Building on Andre's answer, you may want to change this line to be:
visit_records = target_metrics[i].visits.visit;
to go one layer deeper, then do a regular array for loop afterward.

parsing Objects in a loop in javascript

I have a string which I get from an api call and then I parse it into an object using JSON.parse(meetResponse)
meetResponse = {
"returncode":"SUCCESS",
"meetingName":"bbb meeting",
"meetingID":"712",
"createTime":"1457969919738",
"createDate":"Mon Mar 14 11:38:39 EDT 2016",
"voiceBridge":"35014",
"dialNumber":"613-555-1234",
"attendeePW":"PDmAJD4n",
"moderatorPW":"mpassword",
"running":"true",
"duration":"0",
"hasUserJoined":"true",
"recording":"true",
"hasBeenForciblyEnded":"false",
"startTime":"1457969919743",
"endTime":"0","participantCount":"2",
"maxUsers":"20",
"moderatorCount":"2",
"attendees":{
"attendee":[
{
"userID":"10005655",
"fullName":"Snedden Gonsalves",
"role":"MODERATOR",
"customdata":{}
},{
"userID":"10005656",
"fullName":"SneddenReg Gonsalves",
"role":"MODERATOR",
"customdata":{}
}
]
},
"metadata":{},
"messageKey":{},
"message":{}
}
I want to parse 'attendee' under 'attendees' to see who is present
The logic I use right now is :
//check if current user is already present in the meeting
for (var key in meetInfo.attendees.attendee){
console.log('key:',meetInfo.attendees.attendee[key]);
console.log(meetInfo.attendees.attendee[key].userID+"==="+user_id);
if(meetInfo.attendees.attendee[key].userID===user_id){
console.log('in meeting..');
inMeeting=true;
break;
}
else{
inMeeting=false;
}
}
Note:meetInfo is the Whole object
This works is there are more than one attendee but for one attendee it fails.
I am looking for something which would work for any number of 'attendees'.
Also I tried meetInfo.attendees.length instead of Object.keys(meetInfo.attendees).length but it didn't like it

It sounds like your attendees.attendee property could be either an array if multiple, or an object if singular. When it is an array your key variable in the for..in block will be populated the index. When it is an object, it will be populated with the property key.
Two things. First, you can make sure you are always working with an array by concatenating the value with an empty array:
var attendeeList = [].concat(meetInfo.attendees.attendee);
Second, you should not use for..in for iterate through an array. Use a classic for loop instead:
for (var idx= 0; idx < attendeeList.length; idx++)
console.log('key:',attendeeList[idx]);
console.log(attendeeList[idx].userID+"==="+user_id);
if(attendeeList[idx].userID===user_id){
console.log('in meeting..');
inMeeting=true;
break;
} else{
inMeeting=false;
}
}
Bonus, this loop is setting a variable true if any of the items in the array match. There is a special Array function for this:
inMeeting = [].concat(meetInfo.attendees.attendee)
.some(function(a){
return a.userID === user_id;
});

Better data structure to handle this array

I have an array of data get from the server(ordered by date):
[ {date:"2012-8", name:"Tokyo"}, {date:"2012-3", name:"Beijing"}, {date:"2011-10", name:"New York"} ]
I'd like to :
get the name of the first element whose date is in a given year, for example, given 2012, I need Tokyo
get the year of a given name
change the date of a name
which data structure should I use to make this effective ?
because the array could be large, I prefer not to loop the array to find something

Since it appears that the data is probably already sorted by descending date you could use a binary search on that data to avoid performing a full linear scan.
To handle the unstated requirement that changing the date will then change the ordering, you would need to perform two searches, which as above could be binary searches. Having found the current index, and the index where it's supposed to be, you can use two calls to Array.splice() to move the element from one place in the array to another.
To handle searches by name, and assuming that each name is unique, you should create a secondary structure that maps from names to elements:
var map = {};
for (var i = 0, n = array.length; i < n; ++i) {
var name = array[i].name;
map[name] = array[i];
}
You can then use the map array to directly address requirements 2 and 3.
Because the map elements are actually just references to the array elements, changes to those elements will happen in both.

Assuming you are using unique cities, I would use the city names as a map key:
cities = {
Tokyo: {
date: "2012-8"
},
New York: {
date: "2011-10"
}
}
To search by date:
function byDate(date) {
for(el in cities) {
if(cities.hasOwnProperty(el) && cities[el].date === date)
return el;
}
}

Just for the record: without redesigning your date structure you could use sorting combined with the Array filter or map method:
function sortByDate(a,b){
return Number(a.date.replace(/[^\d]+/g,'')) >
Number(b.date.replace(/[^\d]+/g,''));
}
var example = [ {date:"2012-8", name:"Tokyo"},
{date:"2012-3", name:"Beijing"},
{date:"2011-10", name:"New York"} ]
.sort(sortByDate);
//first city with year 2012 (and the lowest month of that year)
var b = example.filter(function(a){return +(a.date.substr(0,4)) === 2012})[0];
b.name; //=> Beijing
//year of a given city
var city = 'Tokyo';
var c = example.filter(function(a){return a.city === city;})[0];
c.year; //=> 2012
//change year of 'New York', and resort data
var city = 'New York', date = '2010-10';
example = example.map(
function(a){if (a.name === city) {a.date = date;} return a;}
).sort(sortByDate);