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Sorting Array in nodejs by date order (recent to oldest)

I'm trying to sort the following array so that the most recent event_end is first
{
"results":[
{
"event_start":"2017-11-27T09:00:00Z",
"event_end":"2017-11-27T09:00:00Z",
"attendance":0,
"title":"Administrate Training Session",
"type":"delegate"
},
{
"event_start":"2018-02-01T09:00:00Z",
"event_end":"2018-02-01T09:00:00Z",
"attendance":0,
"title":"Health and Safety Awareness (HSA)",
"type":"delegate"
},
{
"event_start":"2018-02-19T09:00:00Z",
"event_end":"2018-04-30T09:00:00Z",
"attendance":0,
"title":"SMSTS",
"type":"delegate"
}
]
}
My current code (and this is after trying almost all the different ways to do this is):
Array.from(outcome).sort(sortFunction);
function sortFunction(a, b){
if(b[3] === a[3]){
return 0;
} else {
return (b[3] < a[3]) ? -1 : 1;
}
}
And just to give clarity to how the array is being created:
var history = JSON.parse(body);
var outcome = {};
var key = 'results';
outcome[key] = [];
history.forEach(delegate => {
var data = null;
var sessionKey;
var attendanceCount = 0;
var sessionCount = 0;
var attended = 0;
Array.from(delegate['session_attendance']).forEach(function(val){
if(!val.__proto__.__proto__){
sessionCount++;
}
});
var type;
for(var k in delegate['session_attendance']){
sessionKey = k;
if(k['status'] == true){
attendanceCount++;
}
}
if(attendanceCount == 0){
attended = attendanceCount;
} else {
(attendanceCount / sessionCount) * 100
}
if(delegate['registration']['booking_contact'] !== null){
if(delegate['registration']['booking_contact']['id'] == delegate['contact']['id']){
type = 'booking_contact';
}
} else{
type = 'delegate';
}
data = {
'objectId': delegate['id'],
'title': delegate['event']['title'],
'event_start': delegate['event']['start'],
'event_end': delegate['session_attendance'][sessionKey]['start'],
'attendance': attended,
'type': type
}
outcome[key].push(data);
})
I'm sure its obvious but can anyone point me in the direction of where I am going wrong and how to sort it appropriately?

var obj = {
"results":[
{
"event_start":"2017-11-27T09:00:00Z",
"event_end":"2017-11-27T09:00:00Z",
"attendance":0,
"title":"Administrate Training Session",
"type":"delegate"
},
{
"event_start":"2018-02-01T09:00:00Z",
"event_end":"2018-02-01T09:00:00Z",
"attendance":0,
"title":"Health and Safety Awareness (HSA)",
"type":"delegate"
},
{
"event_start":"2018-02-19T09:00:00Z",
"event_end":"2018-04-30T09:00:00Z",
"attendance":0,
"title":"SMSTS",
"type":"delegate"
}
]
}
obj.results.sort((a, b) => {
return new Date(b.event_end) - new Date(a.event_end)
})
console.log(obj.results)

The function that sort receives get 2 params, each param is an obj, so you can access its properties.
Something like this should work:
arr.sort((a, b) => {
return a.event_end > b.event_end ? -1 : 1;
})

Grouping by fields after reduce is not working in JavaScript

There is a complex object and based on an array which is given as an input I need to modify its properties. Illustration is shown below. If the "field" is same , add them to "or" array .If its different "field" add them to "and" array along with its "value". I am using Set to get keys from both source and input and using them to group based on its keys. Also whenever there are duplicates .ie., suppose the "filterObj" already has the same (field, value) pair. Be it in "and" or inside "or",Then don't add it in the final object
Sandbox: https://codesandbox.io/s/optimistic-mirzakhani-pogpw-so-dpvis
There is a TestCases file in the sandbox which its needs to pass
let filterObj = {
feature: "test",
filter: {
and: [{ field: "field2" }]
}
};
let obj = [{ field: "field2", value: "3" }];
let all_filters = [];
if (filterObj.filter.and && filterObj.filter.and.hasOwnProperty("or")) {
all_filters = [...filterObj.filter.and.or];
} else if (filterObj.filter.and) {
all_filters = [...filterObj.filter.and];
}
const all_objs = [...obj, ...all_filters];
const uniqKeys = all_objs.reduce(
(acc, curr) => [...new Set([...acc, curr.field])],
[]
);
const updateItems = uniqKeys.map(obj => {
const filter_items = all_objs.filter(item => item.field === obj);
let resultObj = {};
if (filter_items && filter_items.length > 1) {
resultObj.or = [...filter_items];
} else if (filter_items && filter_items.length === 1) {
resultObj = { ...filter_items[0] };
}
return resultObj;
});
var result = { ...filterObj, filter: { and: [...updateItems] } };
console.log(result);

Try it.
I redid the implementation, it happened more universally.
Parses any filters according to your algorithm that it finds.
All test cases are worked.
Sandbox link: https://codesandbox.io/s/optimistic-mirzakhani-pogpw-so-i1u6h
let filterObj = {
feature: "test",
filter: {
and: [
{
field: "field1",
value: "2"
}
]
}
};
let obj = [
{
field: "field1",
value: "2"
},
{
field: "field1",
value: "1"
}
];
var FilterController = function(filter) {
var self = this;
self.filter = filter;
// encapsulated map of objects by fields
var storeMap = {};
// counter of objects
var counter = 0;
var tryPutObjectToMap = function(object) {
if (typeof object === "object") {
// get type for grouping
var objectType = self.getObjectGroupType(object);
if (objectType !== null) {
// cheack have group
if (!storeMap.hasOwnProperty(objectType)) {
storeMap[objectType] = [];
}
var duplicate = storeMap[objectType].find(function(sObject) {
return self.getObjectValue(sObject) === self.getObjectValue(object);
});
// check duplicate
if (duplicate === undefined) {
counter++;
storeMap[objectType].push(object);
} else {
// TODO: Handle duplicates
}
} else {
// TODO: handle incorrect object
}
}
};
// get filter structure from map
var getFilterStructureFromMap = function() {
var result = {};
// check exists root filter and filed if have objects
if (counter > 0) {
result["and"] = [];
}
for (var key in storeMap) {
if (storeMap.hasOwnProperty(key)) {
var array = storeMap[key];
if (array.length > 1) {
result["and"].push({
// clone array
or: array.slice()
});
} else {
result["and"].push(array[0]);
}
}
}
return result;
};
// rewrite and get current filter
// if you need^ create new object for result
self.rewriteAndGetFilter = function() {
self.filter.filter = getFilterStructureFromMap();
return self.filter;
};
// not prototype function for have access to storeMap
self.putObjects = function(objects) {
if (Array.isArray(objects)) {
// recursive push array elements
objects.forEach(element => self.putObjects(element));
// handle array
} else if (typeof objects === "object") {
// handle object
if (objects.hasOwnProperty("and") || objects.hasOwnProperty("or")) {
for (var key in objects) {
//no matter `or` or `and` the same grouping by field
// inner object field
if (objects.hasOwnProperty(key)) {
self.putObjects(objects[key]);
}
}
} else {
// filters props not found, try push to store map
tryPutObjectToMap(objects);
}
} else {
// TODO: Handle errors
}
};
if (self.filter.hasOwnProperty("filter")) {
// put and parse current objects from filter
self.putObjects(self.filter.filter);
}
};
// function for grouping objects.
// for you get filed name from object.
// change if need other ways to compare objects.
FilterController.prototype.getObjectGroupType = function(obj) {
if (typeof obj === "object" && obj.hasOwnProperty("field")) {
return obj.field;
}
return null;
};
// get object value
FilterController.prototype.getObjectValue = function(obj) {
if (typeof obj === "object" && obj.hasOwnProperty("value")) {
return obj.value;
}
return null;
};
var ctrl = new FilterController(filterObj);
ctrl.putObjects(obj);
var totalFilter = ctrl.rewriteAndGetFilter();
console.log(totalFilter);
console.log(JSON.stringify(totalFilter));
EDIT 1
I did not change the logic; I made a function based on it.
let filterObj = {
feature: "test",
filter: {
and: [
{
field: "field1",
value: "2"
}
]
}
};
let obj = [
{
field: "field1",
value: 2
},
{
field: "field1",
value: "1"
}
];
function appendToFilter(filter, inputObjects) {
var storeMap = {};
var counter = 0;
var handlingQueue = [];
// if filter isset the appen to handling queue
if (filter.hasOwnProperty("filter")) {
handlingQueue.push(filter.filter);
}
// append other object to queue
handlingQueue.push(inputObjects);
// get first and remove from queue
var currentObject = handlingQueue.shift();
while (currentObject !== undefined) {
if (Array.isArray(currentObject)) {
currentObject.forEach(element => handlingQueue.push(element));
} else if (typeof currentObject === "object") {
if (currentObject.hasOwnProperty("and") || currentObject.hasOwnProperty("or")) {
for (var key in currentObject) {
if (currentObject.hasOwnProperty(key)) {
handlingQueue.push(currentObject[key]);
}
}
} else {
// TODO: append fild exists check
if (currentObject.field) {
if (!storeMap.hasOwnProperty(currentObject.field)) {
storeMap[currentObject.field] = [];
}
var localValue = currentObject.value;
// check duplicate
if (storeMap[currentObject.field].find(object => object.value === localValue) === undefined) {
counter++;
storeMap[currentObject.field].push(currentObject);
}
}
}
}
currentObject = handlingQueue.shift();
}
// create new filter settings
var newFilter = {};
// check exists root filter and filed if have objects
if (counter > 0) { newFilter["and"] = []; }
for (var storeKey in storeMap) {
if (storeMap.hasOwnProperty(storeKey)) {
var array = storeMap[storeKey];
if (array.length > 1) {
newFilter["and"].push({
// clone array
or: array.slice()
});
} else {
newFilter["and"].push(array[0]);
}
}
}
filter.filter = newFilter;
}
// update filterObj
appendToFilter(filterObj, obj);
console.log(filterObj);
EDIT 2,3 (UPDATED)
With others objects support.
export function appendToFilter(filter, inputObjects) {
var storeMap = {};
var others = [];
var counter = 0;
var handlingQueue = [];
// if filter isset the appen to handling queue
if (filter.hasOwnProperty("filter") && filter.filter.hasOwnProperty("and")) {
handlingQueue.push(filter.filter.and);
}
// append other object to queue
handlingQueue.push(inputObjects);
// get first and remove from queue
var currentObject = handlingQueue.shift();
while (currentObject !== undefined) {
if (Array.isArray(currentObject)) {
currentObject.forEach(element => handlingQueue.push(element));
} else if (typeof currentObject === "object") {
if (
currentObject.hasOwnProperty("and") ||
currentObject.hasOwnProperty("or")
) {
for (var key in currentObject) {
if (currentObject.hasOwnProperty(key)) {
handlingQueue.push(currentObject[key]);
}
}
} else {
// TODO: append fild exists check
if (currentObject.field) {
if (!storeMap.hasOwnProperty(currentObject.field)) {
storeMap[currentObject.field] = [];
}
var localValue = currentObject.value;
// check duplicate
if (
storeMap[currentObject.field].find(
object => object.value === localValue
) === undefined
) {
counter++;
storeMap[currentObject.field].push(currentObject);
}
} else {
// handle others objects^ without field "field"
counter++;
others.push(currentObject);
}
}
}
currentObject = handlingQueue.shift();
}
// create new filter settings
var newFilter = {};
// check exists root filter and filed if have objects
if (counter > 0) {
newFilter["and"] = [];
}
for (var storeKey in storeMap) {
if (storeMap.hasOwnProperty(storeKey)) {
var array = storeMap[storeKey];
if (array.length > 1) {
newFilter["and"].push({
// clone array
or: array.slice()
});
} else {
newFilter["and"].push(array[0]);
}
}
}
// Append others to result filter
others.forEach(other => newFilter["and"].push(other));
filter.filter = newFilter;
}

Is there a property in javascript Object.type?

I am studying Node.Js right now and came across this piece of code:
var combine = require('stream-combiner');
var through = require('through2');
var split = require('split');
var zlib = require('zlib');
module.exports = function () {
var grouper = through(write, end);
var current;
function write (line, _, next) {
if (line.length === 0) return next();
var row = JSON.parse(line);
if (row.type === 'genre') {
if (current) {
this.push(JSON.stringify(current) + '\n');
}
current = { name: row.name, books: [] };
}
else if (row.type === 'book') {
current.books.push(row.name);
}
next();
}
function end (next) {
if (current) {
this.push(JSON.stringify(current) + '\n');
}
next();
}
return combine(split(), grouper, zlib.createGzip());
};
Each line the write function gets is a json line that looks like this:
"name": "Neuromancer","genre": "cyberpunk"
And the expected outcome is the following JSON object:
{
"name": "cyberpunk",
"books": [
"Accelerando",
"Snow Crash",
"Neuromancer",
"The Diamond Age",
"Heavy Weather"
]}
and etc.
Basically my question is - what does the row.type means?
Thank you in advance! :D

You put the type parameter in the var row doing
var row = JSON.parse(line);
so that's not a special property o function of the object, it's only, simply, a parameter that was in the JSON (of var line)

Make script works for both input, is possible?

I'm working on this script that takes this as input:
{
"success":true,
"entities":[
{
"pais":{
"id":2,
"nombre":"Bolivia"
}
},
{
"pais":{
"id":5,
"nombre":"Colombia"
}
},
{
"pais":{
"id":6,
"nombre":"Costa Rica"
}
}
],
"idToUpdate":"1"
}
And outputs this: Bolivia, Colombia, Costa Rica. Taking the input example I provide earlier this is how I call the function:
showList('#distTd-' + data.idToUpdate, paisesFromEntity, data.entities);
That's fine but I now I'm getting this input also:
{
"success":true,
"entities":{
"id":5,
"nombre":"dgdfgdfg",
"direccion":"5654645",
"telefono":"656546",
"pais":[
{
"id":1,
"nombre":"Argentina"
},
{
"id":2,
"nombre":"Bolivia"
}
]
}
}
Which differs a bit from the first input so script on this case is not working because the pais key is missing. Can any help me to get ride of this? I can't change the server side that returns the new JSON.
var fullList = [];
$(document).ready(function(){
var uniq = function (arr) {
var ids = {};
arr.forEach(function(obj) {
objPais = obj.pais.id === "undefined" ? obj.id : obj.pais.id;
ids[objPais] = obj;
});
return Object.keys(ids).map(function(id) {
return ids[id];
});
};
function showList(selector) {
var items = [].slice.call(arguments, 1).filter(function(item) { return item; }),
arr = fullList.concat.apply(fullList, items),
list = uniq(arr),
spans = list.map(function(val, i) {
return '<span id="' + val.pais.id +'">' + val.pais.nombre + '</span>';
});
if ($(selector).text().length >0) {
$(selector).append(', ');
}
$(selector).append(spans.join(', '));
}
$("#btn1").on("click", function(){
var arr1 = [{"pais":{"id":1,"nombre":"Country1"}},{"pais":{"id":2,"nombre":"Country2"}}],
arr2 = [{"pais":{"id":1,"nombre":"Country1"}},{"pais":{"id":3,"nombre":"Country3"}},{"pais":{"id":4,"nombre":"Country4"}}],
arr3 =[{"pais":[{"id":1,"nombre":"Argentina"},{"id":2,"nombre":"Bolivia"}]}];
showList('#update', arr1, undefined, arr2, arr3);
});
$("#btn2").on("click", function(){
var arr3 = [{"pais":{"id":5,"nombre":"Country5"}},{"pais":{"id":6,"nombre":"Country6"}}],
arr4 = [{"pais":{"id":7,"nombre":"Country7"}},{"pais":{"id":8,"nombre":"Country8"}}];
showList('#update', arr3, arr4);
});
});
Here is a jsBin working code

Transform second format to first format:
arr3copy = [];
for (var i = 0; i < arr3[0].pais.length; i++) {
arr3copy.push({"pais":{"id":arr3[0].pais[i].id,"nombre":arr3[0].pais[i].nombre}});
};
arr3 = arr3copy;

Getting nested obj value

Given the following obj:
var inputMapping = {
nonNestedItem: "someItem here",
sections: {
general: "Some general section information"
}
};
I'm writing a function to get that data by passing in a string "nonNestedItem" or in the nested case "sections.general". I'm having to use an eval and I was wondering if there was maybe a better way to do this.
Here is what I have so far and it works okay. But improve!
function getNode(name) {
var n = name.split(".");
if (n.length === 1) {
n = name[0];
} else {
var isValid = true,
evalStr = 'inputMapping';
for (var i=0;i<n.length;i++) {
evalStr += '["'+ n[i] +'"]';
if (eval(evalStr) === undefined) {
isValid = false;
break;
}
}
if (isValid) {
// Do something like return the value
}
}
}
Linky to Jsbin

You can use Array.prototype.reduce function like this
var accessString = "sections.general";
console.log(accessString.split(".").reduce(function(previous, current) {
return previous[current];
}, inputMapping));
Output
Some general section information
If your environment doesn't support reduce, you can use this recursive version
function getNestedItem(currentObject, listOfKeys) {
if (listOfKeys.length === 0 || !currentObject) {
return currentObject;
}
return getNestedItem(currentObject[listOfKeys[0]], listOfKeys.slice(1));
}
console.log(getNestedItem(inputMapping, "sections.general".split(".")));

You don't need to use eval() here. You can just use [] to get values from an object. Use a temp object to hold the current value, then update it each time you need the next key.
function getNode(mapping, name) {
var n = name.split(".");
if (n.length === 1) {
return mapping[name];
} else {
var tmp = mapping;
for (var i = 0; i < n.length; i++) {
tmp = tmp[n[i]];
}
return tmp;
}
}