We Keep Coding

converting array to object while considering keys of the same value

I am trying to figure out an easy way to convert an array of objects to an object
I have an array of objects that looks like this:
[
{
"id": "-LP9_kAbqnsQwXq0oGDT",
"value": Object {
"date": 1541482236000,
"title": "First",
},
},
.... more objects here
]
And id like to convert it to an object with the timestamps as the keys, and arrays of objects corresponding to that date. If that key already exists, then add the object to the corresponding array associated with that key
{
1541482236000:
[{
"id": "-LP9_kAbqnsQwXq0oGDT",
"value": Object {
"date": 1541482236000,
"title": "First",
},
},
{
"id": "-LP9_kAbqnsQwXqZZZZ",
"value": Object {
"date": 1541482236000,
"title": "Some other title",
},
},
.... more objects here
],
1541482236001:
[{
"id": "-LP9_kAbqnsQ1234",
"value": Object {
"date": 1541482236001,
"title": "Another title",
},
},
.... more objects here
]
}
I was able to achieve something similar using reduce. However it does not handle adding objects to the array when their key already exists.
calendarReminders = action.value.reduce((obj, reminder) => {
dateKey = moment(reminder.value.date).format('YYYY-MM-DD')
obj[dateKey] = [reminder]
return obj;
}, {});
How can I do this?

You just need to check whether the object is already a key and if not add it with the value of an array. Then you can just push() into it:
let arr = [{"id": "-LP9_kAbqnsQwXq0oGDT","value": {"date": 1541482236000,"title": "First",},},{"id": "SomID","value": {"date": 1541482236000,"title": "Some other title",},},{"id": "A different ID","value": {"date": 1541482236001,"title": "A third title",},}]
let calendarReminders = arr.reduce((obj, reminder) => {
(obj[reminder.value.date] || (obj[reminder.value.date] = [])).push(reminder)
return obj;
}, {});
console.log(calendarReminders)
If you want to set the keys to a different format with moment, you should be able to do that without changing the basic idea.

Please test the below code!
First you iterate through your array of data,
if your result object/dictionary already has the key then you just add the current item
otherwise you make the key and set the value
const data = [];
let result = {};
for (const item of data) {
const key = item.value.date;
if (result.hasOwnProperty(key)) {
const prevData = result[key];
result[key] = [...prevData, item];
} else {
result[key] = [item];
}
}

javascript: looping through nested object/array and adding property

I am not very strong with Javascript. I have a nested array which is a JSON representation of the backend data. It shows a list of proofs and the images used in each proof. Its looks like below:
var project = [{
"proof":"Proof_1",
"images":[
{
"image_id":"12469",
"name":"1911791794.jpg",
},
{
"image_id":"12470",
"name":"1911802897.jpg"
},
{
"image_id":"12471",
"name":"1911761073.jpg"
}
},
{
"proof":"Proof_2",
"images":[
{
"image_id":"12469",
"name":"1911791794.jpg",
},
{
"image_id":"12470",
"name":"1911802897.jpg"
}
}];
I want to add the image_count to each proof section,so that modified data structure looks like this:
var project = [{
"proof":"Proof_1",
"image_count": 3, //<----this is new property I want to add
"images":[
{
"image_id":"12469",
...
I checked some answers but because of my lack of understanding javascript iteration properly I am unable to get this done.
When I do:
for (var proof in project)
{
console.log(proof);
}
I just get 0,1,2...etc printed. I am not getting this, so I help someone in SO will help me understand how to add this property I want.
Thanks in advance.

You can take advantage of Array.prototype.map method:
project = project.map(function (item) {
item.image_count = item.images.length;
return item;
});
Working demo.
Also, as #Sebastian Lasse pointed out - you should name your array using plural form to avoid confusion (projects instead of project).

You can use .map or simple loop
var projects = [{
"proof": "Proof_1",
"images": [{
"image_id": "12469",
"name": "1911791794.jpg",
}, {
"image_id": "12470",
"name": "1911802897.jpg"
}, {
"image_id": "12471",
"name": "1911761073.jpg"
}]
}, {
"proof": "Proof_2",
"images": [{
"image_id": "12469",
"name": "1911791794.jpg",
}, {
"image_id": "12470",
"name": "1911802897.jpg"
}]
}];
projects = projects.map(function (element) {
element.image_count = element.images.length;
return element;
});
console.log(projects);
var len = projects.length, i;
for (i = 0; i < len; i++) {
projects[i].image_count = projects[i].images.length;
}
console.log(projects);

You could - after correcting the missing ] error in your JSON - do this :
project.forEach(function(proof) {
proof.image_count = proof.images.length;
})
demo -> http://jsfiddle.net/dLd8wvpb/

How to parse a JSON array string in JavaScript?

I have an JSON array like this
var filter_value_data = [{"Status":[{"name":"Open","id":"1"},{"name":"Pending","id":"2"},{"name":"Resolved","id":"3"},{"name":"Closed","id":"4"},{"name":"Evaluation","id":"5"}]},{"Payment Status":[{"name":"Paid","id":"10"},{"name":"UnPaid","id":"11"},{"name":"Part Paid","id":"12"}]},{"Priority":[{"name":"Low","id":"6"},{"name":"Medium","id":"7"},{"name":"High","id":"8"},{"name":"Urgent","id":"9"}]}]
I have tried filter_value_data["Status"] which is obviously wrong. How do I get the JSON elements for Status using the names like Status,Payment Status?

filter_value_data is an array (having []), so use filter_value_data[0].Status to get the first element-object with property "Status".
It is always good to format your code in order to see the hierarchy of the structures:
var filter_value_data = [
{
"Status": [
{
"name": "Open",
"id": "1"
}, {
"name": "Pending",
"id": "2"
}, ...
]
}, {
"Payment Status": [
{
"name": "Paid",
"id": "10"
}, ...
]
}, {
"Priority": [
{
"name": "Low",
"id": "6"
}, ...
]
}
];

With your current JSON you can't get the elements with the name alone.
You can get Status with filter_value_data[0]['Status'] and Payment status with filter_value_data[1]['Payment Status'].
This is because the keys are in seperate objects in the array.
In order to get them with filter_value_data['Status'] you need to change your JSON to
var filter_value_data = {
"Status":[
{"name":"Open","id":"1"},
{"name":"Pending","id":"2"},
{"name":"Resolved","id":"3"},
{"name":"Closed","id":"4"},
{"name":"Evaluation","id":"5"}
],
"Payment Status":[
{"name":"Paid","id":"10"},
{"name":"UnPaid","id":"11"},
{"name":"Part Paid","id":"12"}
],
"Priority":[
{"name":"Low","id":"6"},
{"name":"Medium","id":"7"},
{"name":"High","id":"8"},
{"name":"Urgent","id":"9"}
]
};
I wrote this on my phone so it's not as well-formatted as usual. I'll change it ASAP.

With your current JSON, created a result which might be helpful for you.
JS:
$.each(filter_value_data,function(ind,val){
var sta = val.Status; // Status Object get displayed
for(var i=0;i<sta.length;i++){
var idVal= sta[i].id;
var nameVal = sta[i].name;
Statusarray.push(idVal,nameVal);
console.log(Statusarray);
}
})
FiddleDemo

You can use below code, it will return status object
filter_value_data[0]['Status']
filter_value_data[0]['Payment Status']
to get Single value you use :
filter_value_data[0]['Status'][0]['name']

Accessing JSON array's through object properites

Let's say I have the next JSON file:
{
"shows": [
{
"name": "House of cards",
"rating": 8
},
{
"name": "Breaking bad",
"rating": 10
}
]
}
I want to access the rating of a show, by it's name. Something like this:
var rating = data.shows["House of cards"].rating;
Is this possible? Or something similar?
Thanks a lot!

You won't have such hash-style access just by deserializing that JSON sample.
Maybe you might be able to re-formulate how the data is serialized into JSON and use object literals even for shows:
{
"shows": {
"House of cards": {
"rating": 8
}
}
}
And you can still obtain an array of show keys using Object.keys(...):
Object.keys(x.shows);
Or you can even change the structure once you deserialize that JSON:
var x = { shows: {} };
for(var index in some.shows) {
x.shows[some.shows[index].name] = { rating: some.shows[index].rating };
}
// Accessing a show
var rating = x.shows["House of cards"].rating;
I suggest you that it should be better to do this conversion and gain the benefit of accessing your shows using plain JavaScript, rather than having to iterate the whole show array to find one.
When you use object literals, you're accessing properties like a dictionary/hash table, which makes no use of any search function behind the scenes.
Update
OP has concerns about how to iterate shows once it's an associative array/object instead of regular array:
Object.keys(shows).forEach(function(showTitle) {
// Do stuff here for each iteration
});
Or...
for(var showTitle in shows) {
// Do stuff here for each iteration
}
Update 2
Here's a working sample on jsFiddle: http://jsfiddle.net/dst4U/

Try
var rating = {
"shows": [
{
"name": "House of cards",
"rating": 8
},
{
"name": "Breaking bad",
"rating": 10
}
]
};
rating.shows.forEach(findsearchkey);
function findsearchkey(element, index, array) {
if( element.name == 'House of cards' ) {
console.log( array[index].rating );
}
}

Fiddle
var data = {"shows": [{"name": "House of cards","rating": 8},{"name": "Breaking bad","rating": 10}]};
var shows = data.shows;
var showOfRatingToBeFound = "House of cards";
for(var a in shows){
if(shows[a].name == showOfRatingToBeFound){
alert("Rating Of "+ showOfRatingToBeFound+ " is " +shows[a].rating);
}
}

Using jQuery $.each with Json erroring with 1 result

Basically I am transforming a JSON result into html and using $.each it iterate through multiple keys. For example, I am pulling back facebook posts and iterating through the likes in that post.
The problem lies in the fact that when there are multiple "likes" everything works great! although when there is only 1 "like" the "source" key is removed from the result set and my javascript breaks because I expect it to be there. Any idea why the $.each is skipping a level for single nodes? The following is my code:
* JQUERY **
$.each(post.likes.item, function(i, like){
$(currentpost).find('div.cc_likes').append(like + ',');
console.log(like)
});
* JSON RESULT **
* Single Like
likes": {
"item": {
"source": {
"cta": "Mary Smith",
"url": "http:\/\/www.facebook.com\/",
"photo": {
"image": "https:\/\/graph.facebook.com\/"
}
}
},
Result in console:
Object
cta: "MaryAnn Smith"
photo: Object
url: "http://www.facebook.com/"
* Multiple Likes
"likes": {
"item": [
{
"source": {
"cta": "Bobby Carnes Sr.",
"url": "http:\/\/www.facebook.com",
"photo": {
"image": "https:\/\/graph.facebook.com\"
}
}
},
{
"source": {
"cta": "Jenna Purdy",
"url": "http:\/\/www.facebook.com\",
"photo": {
"image": "https:\/\/graph.facebook.com\"
}
}
},
{
"source": {
"cta": "Kevin Say",
"url": "http:\/\/www.facebook.com\",
"photo": {
"image": "https:\/\/graph.facebook.com\"
}
}
}
],
"count": "10",
"count_display": "10"
},
Result in console:
Object
source: Object
cta: "Kevin Smith"
photo: Object
url: "http://www.facebook.com/"

Since $.each() needs an array or array like object as argument, before using the object post.likes.item check if it is an array of not.
Following code will always pass an array to jQuery -
$.each([].concat(post.likes.item), function(i, like){
$(currentpost).find('div.cc_likes').append(like + ',');
console.log(like)
});
Explanation
[] is an empty array in JavaScript. Every array in JavaScript has a concat method.
[].concat(obj) concats obj to the empty array and returns an array.
if obj is not an array, result is [obj] which is an array with one item.
if obj is an array, then result is a deep copy of obj which is already an array.
More about concat method

if ( isArray ) {
for ( ; i < length; i++ ) {
value = callback.call( obj[ i ], i, obj[ i ] );
if ( value === false ) {
break;
}
}
} else {
for ( i in obj ) {
value = callback.call( obj[ i ], i, obj[ i ] );
if ( value === false ) {
break;
}
}
}
That is the jquery code being run on your JSON return. What's happening is, when you are looking at multiple results, it is looping through the array, return each base level object. However, when you are running it on a single return, it is looping through the object properties(in this case, "source"), and returning the value of that property.
You have two choices here. You can either make sure single items are still put in an array, or you can do a check for single items on the client side. The way Moazzam Khan suggests is the best way to do it in most cases.