Develop Reference

Loop through nested array to return values of object

I have a nested array and what I was trying to do was get all the values of the object embedded inside the array. I am currently getting each embedded object and calling Object.values to get the values but this method isn't efficient when the array size is big. Is there a way to loop through the array and return the values of each object? Any help is appreciated. Thanks in advance.
const data = [{"path":"uploads\\20211115000755-package.json"},{"path":"uploads\\20211115012255-index.html"},{"path":"uploads\\20211115014342-dataServerMid.js"},{"path":"uploads\\20211115031212-index.js"},{"path":"uploads\\20211115031218-uploadDataServer.js"},{"path":"uploads\\20211115031232-index.js"},{"path":"uploads\\20211115031244-dataServerMid.js"},{"path":"uploads\\20211115031250-uploadData.css"},{"path":"uploads\\20211115031303-20211115012255-index.html"},{"path":"uploads\\20211115031318-20211115031303-20211115012255-index.html"},{"path":"uploads\\20211115050204-exportsCapture.JPG"},{"path":"uploads\\20211115052347-[FREE] Stunna 4 Vegas x DaBaby x NLE Choppa Type Beat Call of Duty (320 kbps).mp3"},{"path":"uploads\\20211115200304-Readme.docx"},{"path":"uploads\\20211115202751-Visual Artist Series Fall 2019Corrected.docx"},{"path":"uploads\\20211115203354-ln command examples.docx"},{"path":"uploads\\20211115210027-Q2.docx"},{"path":"uploads\\20211116011817-Fall 2019 ABCD Plattsburgh Syllabi Course Description.docx"}]
//change this to loop and return all the values instead of having to call by index
const dataValues = [Object.values(data[0]).toString(), Object.values(data[1]).toString(), Object.values(data[2]).toString()]
console.log(dataValues)
UPDATE: I tried #yousaf's method. It worked for my 3 item array but not for this:
const data = [{
"path": "uploads\\20211115000755-package.json"
}, {
"path": "uploads\\20211115012255-index.html"
}, {
"path": "uploads\\20211115014342-dataServerMid.js"
}, {
"path": "uploads\\20211115031212-index.js"
}, {
"path": "uploads\\20211115031218-uploadDataServer.js"
}, {
"path": "uploads\\20211115031232-index.js"
}, {
"path": "uploads\\20211115031244-dataServerMid.js"
}, {
"path": "uploads\\20211115031250-uploadData.css"
}, {
"path": "uploads\\20211115031303-20211115012255-index.html"
}, {
"path": "uploads\\20211115031318-20211115031303-20211115012255-index.html"
}, {
"path": "uploads\\20211115050204-exportsCapture.JPG"
}, {
"path": "uploads\\20211115052347-[FREE] Stunna 4 Vegas x DaBaby x NLE Choppa Type Beat Call of Duty (320 kbps).mp3"
}, {
"path": "uploads\\20211115200304-Readme.docx"
}, {
"path": "uploads\\20211115202751-Visual Artist Series Fall 2019Corrected.docx"
}, {
"path": "uploads\\20211115203354-ln command examples.docx"
}, {
"path": "uploads\\20211115210027-Q2.docx"
}, {
"path": "uploads\\20211116011817-Fall 2019.docx"
}]
//change this to loop and return all the values instead of having to call by index
const dataValues = data.map((obj, idx) => obj["path" + (idx + 1)])
console.log(dataValues)

Use a for...of to iterate over the array, and then push the value to a new array.
const data=[{path1:"uploads\\20211115000755-package.json"},{path2:"uploads\\20211115012255-index.html"},{path3:"uploads\\20211115014342-dataServerMid.js"}];
const arr = [];
for (const obj of data) {
const [value] = Object.values(obj);
arr.push(value);
}
console.log(arr);
Or you can use map.
const data=[{path1:"uploads\\20211115000755-package.json"},{path2:"uploads\\20211115012255-index.html"},{path3:"uploads\\20211115014342-dataServerMid.js"}];
const arr = data.map(obj => {
const [value] = Object.values(obj);
return value;
});
console.log(arr);

Use for loop for iterate data
const data = [{
"path1": "uploads\\20211115000755-package.json"
}, {
"path2": "uploads\\20211115012255-index.html"
}, {
"path3": "uploads\\20211115014342-dataServerMid.js"
}]
const dataValues = [];
for(var i = 0; i < data.length; i++)
{
dataValues.push(Object.values(data[i]).toString())
}
console.log(dataValues)

This may help You. Try it out..
function nestedLoop(obj) {
const res = {};
function recurse(obj, current) {
for (const key in obj) {
let value = obj[key];
if(value != undefined) {
if (value && typeof value === 'object') {
recurse(value, key);
} else {
// Do your stuff here to var value
res[key] = value;
}
}
}
}
recurse(obj);
return res;
}

How to add duplicate key elements in JavaScript Object?

I want to make the following newArray using by following testArray.
newArray↓
let newArray = [
{section:"business",name:["Bob","John"]},
{section:"H&R",name:["Jen","Bobby"]},
]
testArray↓
let test = [
{section:"business",name:"Bob"},
{section:"business",name:"John"},
{section:"H&R",name:"Jen"},
{section:"H&R",name:"Bobby"},
]
First of all, I tried to find some key elements using by filter method like below.
let newArray = test.filter((x:any,i,self)=>
self.indexOf(x.section)===i
)
but this code output is [].
So, how do I make code to get my expected output?
Does anyone help me?

Use Array.reduce():
let test=[{section:"business",name:"Bob"},{section:"business",name:"John"},{section:"H&R",name:"Jen"},{section:"H&R",name:"Bobby"}];
let newArray = test.reduce((acc,cur) => {
if(acc.some(el => el.section === cur.section)){
acc.forEach((el,idx) => {
if(el.section === cur.section){
acc[idx].name.push(cur.name)
}
})
}else{
cur.name = [cur.name]
acc.push(cur)
}
return acc
},[])
console.log(newArray)

you can try this
const test = [{
section: "business",
name: "Bob"
},
{
section: "business",
name: "John"
},
{
section: "H&R",
name: "Jen"
},
{
section: "H&R",
name: "Bobby"
},
];
// gather sections
const sections = {};
test.forEach(t => {
sections[t.section] = sections[t.section] || [];
sections[t.section].push(t.name);
});
// convert sessions to array
const newArray = Object.keys(sections).map(k => {
return {
section: k,
name: sections[k]
};
});
console.log(newArray);

Convert an array to json object by javascript

I am stuck to solve this problem.
Convert an array below
var input = [
'animal/mammal/dog',
'animal/mammal/cat/tiger',
'animal/mammal/cat/lion',
'animal/mammal/elephant',
'animal/reptile',
'plant/sunflower'
]
to json Object
var expectedResult = {
"animal": {
"mammal": {
"dog": true,
"cat": {
"tiger": true,
"lion": true
},
"elephant": true
},
"reptile": true
},
"plant": {
"sunflower": true
}
}
Which data structure and algorithm can I apply for it?
Thanks

You need to first split each element to convert to array
using reverse reduce method you can convert them to object.
And your last step is merge this objects.
Lodash.js merge method is an one way to merge them.
var input = ['animal/mammal/dog','animal/mammal/cat/tiger','animal/mammal/cat/lion', 'animal/mammal/elephant','animal/reptile', 'plant/sunflower']
var finalbyLodash={}
input.forEach(x=>{
const keys = x.split("/");
const result = keys.reverse().reduce((res, key) => ({[key]: res}), true);
finalbyLodash = _.merge({}, finalbyLodash, result);
});
console.log(finalbyLodash);
<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.10/lodash.js"></script>

To make the process more understandable, break the problem down into pieces.
The first step is convert each string into something we can use, converting this:
"animal/mammal/dog"
into this:
[ "animal", "mammal", "dog" ]
That's an array of property names needed to build the final object.
Two functions will accomplish this for you, String.prototype.split() to split the string into an array, and Array.prototype.map() to transform each of the array elements:
let splitIntoNames = input.map(str => str.split('/'));
The intermediate result is this:
[
[ "animal", "mammal", "dog" ],
[ "animal", "mammal", "cat", "tiger" ],
[ "animal", "mammal", "cat", "lion" ],
[ "animal", "mammal", "elephant" ],
[ "animal", "reptile" ],
[ "plant", "sunflower" ]
]
Next step is to iterate over each array, using Array.prototype.forEach() to add properties to the object. You could add properties to the object with a for loop, but let's do that with a recursive function addName():
function addName(element, list, index) {
if (index >= list.length) {
return;
}
let name = list[index];
let isEndOfList = index === list.length - 1;
element[name] = element[name] || (isEndOfList ? true : {});
addName(element[name], list, index + 1);
}
let result = {};
splitIntoNames.forEach((list) => {
addName(result, list, 0);
});
The result:
result: {
"animal": {
"mammal": {
"dog": true,
"cat": {
"tiger": true,
"lion": true
},
"elephant": true
},
"reptile": true
},
"plant": {
"sunflower": true
}
}
const input = [
"animal/mammal/dog",
"animal/mammal/cat/tiger",
"animal/mammal/cat/lion",
"animal/mammal/elephant",
"animal/reptile",
"plant/sunflower",
];
let splitIntoNames = input.map((str) => str.split("/"));
console.log("splitIntoNames:", JSON.stringify(splitIntoNames, null, 2));
function addName(element, list, index) {
if (index >= list.length) {
return;
}
let name = list[index];
let isEndOfList = index === list.length - 1;
element[name] = element[name] || (isEndOfList ? true : {});
addName(element[name], list, index + 1);
}
let result = {};
splitIntoNames.forEach((list) => {
addName(result, list, 0);
});
console.log("result:", JSON.stringify(result, null, 2));

You can create a function that will slice every element from the array by "/" than you put the results into a variable and than just mount the Json. I mean something like that below:
window.onload = function() {
var expectedResult;
var input = [
'animal/mammal/dog',
'animal/mammal/cat/tiger',
'animal/mammal/cat/lion',
'animal/mammal/elephant',
'animal/reptile',
'plant/sunflower'
]
input.forEach(element => {
var data = element.split('/');
var dog = data[2] === 'dog' ? true : false
var tiger = data[2] === 'cat' && data[3] === 'tiger' ? true : false
var lion = data[2] === 'cat' && data[3] === 'lion' ? true : false
expectedResult = {
data[0]: {
data[1]: {
"dog": dog,
"cat": {
"tiger": tiger,
"lion": lion
}
}
}
}
})
}

Late to the party, here is my try. I'm implmenting recursive approach:
var input = ['animal/mammal/dog', 'animal/mammal/cat/tiger', 'animal/mammal/cat/lion', 'animal/mammal/elephant', 'animal/reptile', 'plant/sunflower'];
result = (buildObj = (array, Obj = {}) => {
array.forEach((val) => {
keys = val.split('/');
(nestedFn = (object) => {
outKey = keys.shift();
object[outKey] = object[outKey] || {};
if (keys.length == 0) object[outKey] = true;
if (keys.length > 0) nestedFn(object[outKey]);
})(Obj)
})
return Obj;
})(input);
console.log(result);

I try with array reduce, hope it help
let input = [
"animal/mammal/dog",
"animal/mammal/cat/tiger",
"animal/mammal/cat/lion",
"animal/elephant",
"animal/reptile",
"plant/sunflower",
];
let convertInput = (i = []) =>
i.reduce((prev, currItem = "") => {
let pointer = prev;
currItem.split("/").reduce((prevPre, currPre, preIdx, arrPre) => {
if (!pointer[currPre]) {
pointer[currPre] = preIdx === arrPre.length - 1 ? true : {};
}
pointer = pointer[currPre];
}, {});
return prev;
}, {});
console.log(JSON.stringify(convertInput(input), null, 4));

convert JSON object to a different one

i have this json:
[
{
"AF28110": 33456.75,
"AF27989": 13297.26
}
]
and i want to convert it to:
[
{ "name": "AF28110", "price": 33456.75},
{ "name": "AF27989", "price": 13297.26}
]
I have tried various making it with .map() but i cannot make it work.
does anyone have any idea how to do this?
thank you

You can try following code:
let output = [];
input.forEach(obj => Object.getOwnPropertyNames(obj).forEach(key => output.push({name: key, price: obj[key]})))
Object.getOwnPropertyNames will give you names of your properties and then you can transform each name to a separate output array item.

Using map:
const data = [
{
"AF28110": 33456.75,
"AF27989": 13297.26
}
]
const out = Object.keys(data[0]).map(el => {
return { name: el, price: data[0][el] };
});
console.log(out)

Here's a way using concat, Object.keys, and map. You can take each item from the array, get the keys from that object, and then map each key to the name/price object you want. Do that for each item, then flatten the result (using concat).
Example:
const arr = [{
"AF28110": 33456.75,
"AF27989": 13297.26
}]
const result = [].concat(...arr.map(o => Object.keys(o).map(k => ({name: k, price: o[k]}))))
console.log(result);

If you have multiple objects on the array, you can use reduce
let arr = [
{"AF28110": 33456.75,"AF27989": 13297.26},
{"AF28111": 33456.20,"AF27984": 13297.88}
];
let result = arr.reduce((c, v) => c.concat(Object.entries(v).map(o => {return {name: o[0],price: o[1]}})), []);
console.log(result);

Try this,
var text = '[{"AF28110": 33456.75,"AF27989": 13297.26}]';
var obj = JSON.parse(text);
var result = [];
for (i = 0; i < obj.length; i++) {
var keys = Object.keys(obj[i]);
for (j = 0; j < keys.length; j++){
result[j] = '{ "name":' +keys[j] + ', "price":' + obj[i][keys[j]]+'}';
}
}
console.log(result);
Thanks.

Ways to achieve :
Using Object.keys method :
var jsonObj = [
{
"AF28110": 33456.75,
"AF27989": 13297.26
}
];
var res = Object.keys(jsonObj[0]).map(item => {
return {"name": item, "price": jsonObj[0][item] };
});
console.log(res);
Using Object.getOwnPropertyNames method :
var jsonObj = [
{
"AF28110": 33456.75,
"AF27989": 13297.26
}
];
var res = Object.getOwnPropertyNames(jsonObj[0]).map(item => {
return {"name": item, "price": jsonObj[0][item] };
});
console.log(res);

Summarize count of occurrences in an array of objects with Array#reduce

I want to summarize an array of objects and return the number of object occurrences in another array of objects. What is the best way to do this?
From this
var arrayOfSongs = [
{"title":"Blue","duration":161.71,"audioUrl":"/assets/music/blue","playing":false,"playedAt":"2016-12-21T22:58:55.203Z"},
{"title":"Blue","duration":161.71,"audioUrl":"/assets/music/blue","playing":false,"playedAt":"2016-12-21T22:58:55.203Z"},
{"title":"Blue","duration":161.71,"audioUrl":"/assets/music/blue","playing":false,"playedAt":"2016-12-21T22:58:55.203Z"},
{"title":"Green","duration":161.71,"audioUrl":"/assets/music/blue","playing":false,"playedAt":"2016-12-21T22:58:55.203Z"}
];
To this
var newArrayOfSongs = [
{"title": "Blue", "playCount": 3 },
{"title": "Green", "playCount": 1}
]
I have tried
arrayOfSongs.reduce(function(acc, cv) {
acc[cv.title] = (acc[cv.title] || 0) + 1;
return acc;
}, {});
}
But it returns an object:
{ "Blue": 3, "Green": 1};

You should pass the initial argument to the reduce function as an array instead of object and filter array for the existing value as below,
Working snippet:
var arrayOfSongs = [
{"title":"Blue","duration":161.71,"audioUrl":"/assets/music/blue","playing":false,"playedAt":"2016-12-21T22:58:55.203Z"},
{"title":"Blue","duration":161.71,"audioUrl":"/assets/music/blue","playing":false,"playedAt":"2016-12-21T22:58:55.203Z"},
{"title":"Blue","duration":161.71,"audioUrl":"/assets/music/blue","playing":false,"playedAt":"2016-12-21T22:58:55.203Z"},
{"title":"Green","duration":161.71,"audioUrl":"/assets/music/blue","playing":false,"playedAt":"2016-12-21T22:58:55.203Z"}
];
var newArrayOfSongs = arrayOfSongs.reduce(function(acc, cv) {
var arr = acc.filter(function(obj) {
return obj.title === cv.title;
});
if(arr.length === 0) {
acc.push({title: cv.title, playCount: 1});
} else {
arr[0].playCount += 1;
}
return acc;
}, []);
console.log(newArrayOfSongs);

To build on what you already have done, the next step is to "convert" the object to an array
var arrayOfSongs = [
{"title":"Blue","duration":161.71,"audioUrl":"/assets/music/blue","playing":false,"playedAt":"2016-12-21T22:58:55.203Z"},
{"title":"Blue","duration":161.71,"audioUrl":"/assets/music/blue","playing":false,"playedAt":"2016-12-21T22:58:55.203Z"},
{"title":"Blue","duration":161.71,"audioUrl":"/assets/music/blue","playing":false,"playedAt":"2016-12-21T22:58:55.203Z"},
{"title":"Green","duration":161.71,"audioUrl":"/assets/music/blue","playing":false,"playedAt":"2016-12-21T22:58:55.203Z"}
];
var obj = arrayOfSongs.reduce(function(acc, cv) {
acc[cv.title] = (acc[cv.title] || 0) + 1;
return acc;
}, {});
// *** added code starts here ***
var newArrayOfSongs = Object.keys(obj).map(function(title) {
return {
title: title,
playCount:obj[title]
};
});
console.log(newArrayOfSongs);

I recommend doing this in two stages. First, chunk the array by title, then map the chunks into the output you want. This will really help you in future changes. Doing this all in one pass is highly complex and will increase the chance of messing up in the future.
var arrayOfSongs = [
{"title":"Blue","duration":161.71,"audioUrl":"/assets/music/blue","playing":false,"playedAt":"2016-12-21T22:58:55.203Z"},
{"title":"Blue","duration":161.71,"audioUrl":"/assets/music/blue","playing":false,"playedAt":"2016-12-21T22:58:55.203Z"},
{"title":"Blue","duration":161.71,"audioUrl":"/assets/music/blue","playing":false,"playedAt":"2016-12-21T22:58:55.203Z"},
{"title":"Green","duration":161.71,"audioUrl":"/assets/music/blue","playing":false,"playedAt":"2016-12-21T22:58:55.203Z"}
];
function chunkByAttribute(arr, attr) {
return arr.reduce(function(acc, e) {
acc[e[attr]] = acc[e[attr]] || [];
acc[e[attr]].push(e);
return acc;
}, {});
}
var songsByTitle = chunkByAttribute(arrayOfSongs, 'title');
var formattedOutput = Object.keys(songsByTitle).map(function (title) {
return {
title: title,
playCount: songsByTitle[title].length
};
});
There, now everything is named according to what it does, everything does just one thing, and is a bit easier to follow.

https://jsfiddle.net/93e35wcq/
I used a set object to get the unique track titles, then used Array.map to splice those and return a song object that contains play count inside the track title.
The Data:
var arrayOfSongs = [{
"title": "Blue",
"duration": 161.71,
"audioUrl": "/assets/music/blue",
"playing": false,
"playedAt": "2016-12-21T22:58:55.203Z"
}, {
"title": "Blue",
"duration": 161.71,
"audioUrl": "/assets/music/blue",
"playing": false,
"playedAt": "2016-12-21T22:58:55.203Z"
}, {
"title": "Blue",
"duration": 161.71,
"audioUrl": "/assets/music/blue",
"playing": false,
"playedAt": "2016-12-21T22:58:55.203Z"
}, {
"title": "Green",
"duration": 161.71,
"audioUrl": "/assets/music/blue",
"playing": false,
"playedAt": "2016-12-21T22:58:55.203Z"
}];
The Function:
function getPlayCount(arrayOfSongs) {
let songObj = {};
let SongSet = new Set();
arrayOfSongs.map(obj => (SongSet.has(obj.title)) ? true : SongSet.add(obj.title));
for (let songTitle of SongSet.values()) {
songObj[songTitle] = {
playCount: 0
};
arrayOfSongs.map(obj => (obj.title === songTitle) ? songObj[songTitle].playCount++ : false)
}
return songObj;
}
console.log(getPlayCount(arrayOfSongs));
Which isn't exactly what you wanted formatting wise, but if you're married to it, this will do the trick:
function getPlayCount(arrayOfSongs) {
let songObj = {};
let SongSet = new Set();
arrayOfSongs.map(obj => (SongSet.has(obj.title)) ? true : SongSet.add(obj.title));
for (let songTitle of SongSet.values()) {
songObj[songTitle] = 0;
arrayOfSongs.map(obj => (obj.title === songTitle) ? songObj[songTitle]++ : false)
}
return songObj;
}
console.log(getPlayCount(arrayOfSongs));
https://jsfiddle.net/93e35wcq/1/