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Javascript object to list objects

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JS: преобразуем объект в массив

У нас есть как минимум 3 способа, чтобы конвертировать объект в массив.

В массиве есть массив методов. Преобразовав объект в массив, вы получите доступ ко всему этому. Юху! 🥳

const zoo = < lion: '🦁', panda: '🐼', >; Object.keys(zoo); // ['lion', 'panda'] Object.values(zoo); // ['🦁', '🐼'] Object.entries(zoo); // [ ['lion', '🦁'], ['panda', '🐼'] ]

Время для истории

Древние времена

Давным-давно, в далекой галактике, проходиться по объектам было не так-то просто. Ок, я немного преувеличил 😅. Но я помню, что всякий раз, когда мне нужно было преобразовать объект в массив, мне приходилось делать что-то вроде этого.

var numbers = < one: 1, two: 2, >; var keys = []; for (var number in numbers) < if (numbers.hasOwnProperty(number)) < keys.push(number); >> keys; // [ 'one', 'two' ]

Я все время был зол и хотел найти лучший способ.

ES6 — Object.keys

И тут появился ES6! Моя жизнь изменилась! Наконец-то у нас есть более простой способ 🥳

Теперь был встроенный метод, который быстро превращает все ключи в моем объекте в массив:

const numbers = < one: 1, two: 2, >; Object.keys(numbers); // [ 'one', 'two' ]

Жизнь была прекрасна! Но потом я снова рассердился. Почему я могу извлекать только ключи, мне тоже нужны значения! Люди всегда хотят большего, не так ли 😂 А потом появился ES2017…

Object.values

Привет, я ES2017 и исполняю все твои пожелания. Теперь вы можете легко извлечь значения в массив одним методом.

const numbers = < one: 1, two: 2, >; Object.values(numbers); // [ 1, 2 ]

Object.entries

Но ES2017 на этом не остановился. Сейчас я могу получить и ключи, и значения. Я потрясен.

const numbers = < one: 1, two: 2, >; Object.entries(numbers); // [ ['one', 1], ['two', 2] ]

Object.entries + Деструктуризация

const numbers = < one: 1, >; const objectArray = Object.entries(numbers); objectArray.forEach((Javascript object to list objects) => < console.log(key); // 'one' console.log(value); // 1 >);

Конец истории

А теперь идите и поиграйтесь со всеми этими удивительными методами 😊

Поддержка браузерами

У Object.keys лучшая поддержка. Когда я говорю лучшая — это означает, что его поддерживает Internet Explorer. Object.values и Object.entries, к сожалению, не поддерживаются IE. Но всегда есть полифил для них.

Polyfill

Но это еще не все!

Ваш следующий вопрос может заключаться в том, как мне преобразовать массив обратно в объект. Есть новый метод Object.fromEntries. По сути, это противоположность Object.entries.

const array = [ [‘one’, 1], [‘two’, 2], ]; Object.fromEntries(array); //

Это очень новый метод, так что поддержка есть не везде.

Читайте также:  Php creating a button

Оригинал статьи: ссылка Автор статьи: Alex. Категория: JavaScript
Дата публикации: 18.01.2021

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Javascript object to list objects

Last updated: Jan 7, 2023
Reading time · 3 min

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# Table of Contents

# Convert an Object to an Array of Objects in JavaScript

Use the Object.values() method to convert an object to an array of objects, e.g. const arr = Object.values(obj) .

The Object.values() method takes an object as a parameter and returns an array containing the object’s property values.

Copied!
const obj =  emp1:  id: 1, name: 'Alice', >, emp2:  id: 2, name: 'Bob', >, >; const arrayOfObjects = Object.values(obj); // 👇️ [ < id: 1, name: 'Alice' >, < id: 2, name: 'Bob' >] console.log(arrayOfObjects);

The Object.values() method returns an array containing the object’s values.

Notice that the keys of the object get automatically removed. If you need to preserve the keys, look at the last subheading.

Here’s an example of using the Object.values() method without nested properties.

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// 👇️ ['bobby', 'Chile'] console.log(Object.values(name: 'bobby', country: 'Chile'>));

# Convert an Object to an Array of Objects using Object.keys()

You can also use the Object.keys method to convert an object to an array of objects.

Copied!
const obj =  emp1:  id: 1, name: 'Alice', >, emp2:  id: 2, name: 'Bob', >, >; const arrayOfObjects = Object.keys(obj).map(key => obj[key]); // 👇️ [, ] console.log(arrayOfObjects);

The Object.keys() method returns an array of the object’s keys.

Copied!
const obj =  emp1:  id: 1, name: 'Alice', >, emp2:  id: 2, name: 'Bob', >, >; console.log(Object.keys(obj)); // 👉️ [ 'emp1', 'emp2' ]

The function we passed to the Array.map() method gets called with each element in the array.

On each iteration, we return the value of each key.

The map() method returns a new array containing the values returned from the callback function.

# Convert an Object to an Array of Objects using Object.entries()

The Object.entries() method can be used to transform the object into an array of key-value pairs.

Copied!
const obj =  emp1:  id: 1, name: 'Alice', >, emp2:  id: 2, name: 'Bob', >, >; // [ // [ 'emp1', < id: 1, name: 'Alice' >], // [ 'emp2', < id: 2, name: 'Bob' >] // ] console.log(Object.entries(obj));

You can use the Array.map() method to return only the value of each key.

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const obj =  emp1:  id: 1, name: 'Alice', >, emp2:  id: 2, name: 'Bob', >, >; const arrayOfObjects = Object.entries(obj).map(entry => entry[1]); // 👇️ [, ] console.log(arrayOfObjects);

# Convert an Object to an Array preserving the nested keys

You can also use the Object.entries() method to preserve the nested keys of the object when converting it to an array of objects.

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const obj =  emp1:  id: 1, name: 'Alice', >, emp2:  id: 2, name: 'Bob', >, >; const withNestedKeys = Object.entries(obj).map(entry =>  return [entry[0]]: entry[1]>; >); // [ // < emp1: < id: 1, name: 'Alice' >>, // < emp2: < id: 2, name: 'Bob' >> // ] console.log(withNestedKeys);

We used the Array.map() method to iterate over the array.

On each iteration, we return an object and preserve the key-value pair structure of the original object.

When you use this approach all of the key-value pairs of the object get transferred to the objects in the array.

# Additional Resources

You can learn more about the related topics by checking out the following tutorials:

I wrote a book in which I share everything I know about how to become a better, more efficient programmer.

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How to list elements from an object of data with javascript

Solution 1: You can use map To get from Solution 2: Sounds to me like you need to use a constructor function and then ‘construct’ or return objects from that and store in your set: jsFiddle Solution 3: One solution : Solution 4: Which gives: The only thing left to add is an end condition, so that if there are no more values left the recursion just returns (otherwise we’d loop forever): Full solution That’s it!

How to list elements from an object of data with javascript

How can I build a ul list element as below from the array values of each product using javascript (maybe with jQuery)?

  • level1_group19
    • level2_group36
    • level2_group27
      • level3_group37
      • level2_group30

      As a first step, you can iterate over all properties of the object like that:

      let result = <>; for (let property in productObject) < if (!productObject.hasOwnProperty(property)) < continue; >// Add groups to result hierarchy // Something like: result[productObject[property][0]] = <>; >

      Further I really get your logic, because the hierarchy in the arrays is not given.

      I expect, that you want somehow loop over the array and check the level?

      Then you could add it to the final hiearachy in a result object, and iterate finally over this, to display it.

      I have it working in my case, here it is.

      Get a Unique List of Objects in an Array of Object in JavaScript

      To the tutorial! : https://yagisanatode.com/2021/07/03/get-a-unique-list-of-objects-in-an-array Duration: 20:35

      Creating a List Object from Array in Javascript

      I am going through Javascript from the beginning. No shortcuts, no framework, nothing. Just plain Javascript. And just for the fun of it, I am doing every exercise. Now, when I get to this one question:

      Write a function arraytolist that builds up a data structure like

      My code has to be able to fulfill the following:

      console.log(arrayToList([10, 20])); // → >

      I tried to do this recursively as the later question wants us to do it recursively (recursion is one of my weakest points!). But, I got the following code up:

      var list = < value: 0, rest: null >function arrayToList(array) < list.value = array.shift(); if(array.length!=0) < list.rest = arrayToList(array); >else < list.rest = null; console.log(list); //this outputs to return list; > return list; >;

      The . refers to the same block of

      Well, I did not expand to the end to see (its too long! (after about 20 times opening is still the same) IF there is an end at all).

      Hoping to have someone guide me to the answer. I have spent couple of days on this already and am stuck.

      Thanks a lot and have a good day all!

      Guidance (hopefully!)

      You do not need a global list variable, like you're currently using (unless you're trying to do some complex optimisation – don't worry about it for now). In fact, it looks like this global list variable is what's causing your problems. I will try to walk you through the correct way to do this from the beginning.

      First, try to identify what the 'repeated' part of the output needs to looks like. In your case, the repeated part is:

      because if you swap RECURSION for that SAME structure above, you get the exact cascading effect you need:

      Once you've identified that, your function literally just needs to return that object. It is that simple . Swap someValue for that front value (i.e. the return value of arr.shift() ), and swap RECURSION for a call back to your function, passing it the rest of the array. Which gives:

      The only thing left to add is an end condition, so that if there are no more values left the recursion just returns null (otherwise we'd loop forever):

      Full solution

      function arrayToList(arr) < if (arr.length === 0) < return null; >var value = arr.shift(); return < value: value, rest: arrayToList(arr) >; >console.log(arrayToList([10, 20])); // >

      That's it! Does that make sense?

      You need to keep a list of the last item that you added, as this will be the item that you add the next one to.

      var list = null;function arrayToList(array) < var last = null; for (var i = 0; i < array.length; i++) < var item = < value: array[i], rest: null >; if (last == null) list = item; else last.rest = item; last = item; > return list; >console.log(arrayToList([10, 20]));

      Create object from array, Simply do Object.assign(yourArray, <>) and you will get your desired result. If you instead want to merge your array of objects into another

      How to create a javascript function that output a list of object with a list of the object's property?

      I have a piece of javascript that looks like the following

      Since property1 and property2 are both empty for all objects, I want to automate this such that I only need to keep track of the name. Something like:

      namelist = ['a', 'b', 'c']; magicFunction(namelist);

      that magicFunction can return that set I mentioned above. I am very new to javascript, if you think this is too rudimentary for stackoverflow, please give me a few keywords so I know what I should be searching for. Thanks!

      You can use map 

      var namelist = ['a', 'b', 'c']; var set = namelist.map(function(e) < return < name: e, property1: 0, property2: 0 >>); 
      function magicFunction(arr) < return arr.map(function(e) < return < name: e, property1: 0, property2: 0 >>); >var namelist = ['a', 'b', 'c']; set = magicFunction(namelist);console.log(set); document.getElementById('output').innerHTML = JSON.stringify(set, 0, 2);

      Sounds to me like you need to use a constructor function and then 'construct' or return objects from that and store in your set:

      // quick array var someArray = ['a', 'b', 'c']; // define array for output var set = []; // constructor to create the objects function something(name, param1, param2) < this.name = name; this.property1 = param1; this.property2 = param2; >// run through the quick array and build the objects with the constructor - push into 'set' var magicFunction = function(arrayName) < for (var i = 0; i < arrayName.length; i++) < set.push( new something( someArray[i] ) ); >> magicFunction(someArray); console.log(set); 
      /* instead of console.log */ function log(val)< document.write('
      ' + JSON.stringify( val , null , ' ') + '
       
      '); >;function magicFunction( listOfNames ) < return listOfNames.map(function( currentValue )< return < name : currentValue , property1 : '', property2 : '', >; >) >;var namelist = ['a', 'b', 'c' , 'd' , 'e' , 'f']; log( magicFunction(namelist) );
       
      function magicFunction(nameList) < var set = [];for(var i = 0; ireturn set; >
       
      Object.keys(), Object.keys() returns an array whose elements are strings corresponding to the enumerable properties found directly upon object . The ordering of the properties
       
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