How to Sort an Array of Objects in JavaScript

How to Sort an Array of Objects in JavaScript

In this article, I’ll show you how to sort an array of objects in JavaScript with no fuss or bother.

In this article, I’ll show you how to sort an array of objects in JavaScript with no fuss or bother.

If you have an array of objects that you need to sort into a certain order, the temptation might be to reach for a JavaScript library. Before you do however, remember that you can do some pretty neat sorting with the native Array.sort function.

To follow along with this article, you will need a knowledge of basic JavaScript concepts, such as declaring variables, writing functions, and conditional statements. I’ll also be using ES6 syntax.

Basic Array Sorting

By default, the JavaScript Array.sort function converts each element in the array to be sorted, into a string, and compares them in Unicode code point order.

const foo = [8, 3, 5, 'whistle', 'fish'];
foo.sort(); // returns [3, 5, 8, 'fish', 'whistle']

const bar = [4, 19, 30, function(){}, {key: 'value'}];
bar.sort(); // returns [ 19, 30, 4, { key: 'value' }, [Function] ]


You may be wondering why 30 comes before 4. Not logical, huh? Well, actually it is. This happens because each element in the array is first converted to a string, and "30" comes before "4" in Unicode order.

It’s also worth noting that unlike many other JavaScript array functions, Array.sort actually changes, or mutates the array it sorts.

const baz = ['hello world', 31, 5, 9, 12];
baz.sort(); // baz array is modified
console.log(baz); // shows [12, 31, 5, 9, "hello world"]


To avoid this, you can create a new instance of the array to be sorted and modify that instead.

const baz = ['hello world', 31, 5, 9, 12];
const newBaz = [...baz].sort(); // new instance of baz array is created and sorted
console.log(baz); // "hello world", 31, 5, 9, 12]
console.log(newBaz); // [12, 31, 5, 9, "hello world"]


Note the use of the spread operator to create a new instance of baz. You can read more about that here.

Try it out

JS Bin on jsbin.com

Using Array.sort alone would not be very useful for sorting an array of objects. Thankfully, the function takes an optional compareFunction parameter, which causes the array elements to be sorted according to the return value of the compare function.

Using Compare Functions to Sort

Let’s say that a and b are the two elements being compared by the compare function. If the return value of the compare function is:

  1. less than 0 — a comes before b
  2. greater than 0 — b comes before a
  3. equal to 0 — a and b are left unchanged with respect to each other

Let’s look at a simple example with an array of numbers:

const arr = [1, 2, 30, 4];

function compare(a, b){
  if (a > b) return 1;
  if (b > a) return -1;

  return 0;
}

arr.sort(compare);
// => 1, 2, 4, 30


This can be refactored somewhat to obtain the return value by subtracting a from b:

function compare(a, b){
  return a - b;
}


This is now a good candidate for an arrow function:

arr.sort((a, b) => a - b);


If you’re not familiar with arrow functions, you can read more about them here: ES6 Arrow Functions: Fat and Concise Syntax in JavaScript.

Sort an Array of Objects in JavaScript

Now let’s look at sorting an array of objects. Let’s take an array of band objects:

const bands = [
  { genre: 'Rap', band: 'Migos', albums: 2},
  { genre: 'Pop', band: 'Coldplay', albums: 4},
  { genre: 'Rock', band: 'Breaking Benjamins', albums: 1}
];


We can use the following compare function to sort this array of objects according to genre:

function compare(a, b) {
  // Use toUpperCase() to ignore character casing
  const genreA = a.genre.toUpperCase();
  const genreB = b.genre.toUpperCase();

  let comparison = 0;
  if (genreA > genreB) {
    comparison = 1;
  } else if (genreA < genreB) {
    comparison = -1;
  }
  return comparison;
}

bands.sort(compare);

/* returns [
{ genre: 'Pop', band: 'Coldplay', albums: 4 },
{ genre: 'Rap', band: 'Migos', albums: 2 },
{ genre: 'Rock', band: 'Breaking Benjamins', albums: 1 }
] */


To reverse the sorting order, you can simply invert the return value of the compare function:

function compare(a, b) {
  ...

  //invert return value by multiplying by -1
  return comparison * -1;
}


Try it out

JS Bin on jsbin.com

Creating a Dynamic Sorting Function

Let’s finish up by making this more dynamic. Let’s create a sorting function, which you can use to sort an array of objects, whose values are either strings or numbers. This function has two parameters — the key we want to sort by and the order of the results (i.e. ascending or descending).

const bands = [
  { genre: 'Rap', band: 'Migos', albums: 2},
  { genre: 'Pop', band: 'Coldplay', albums: 4, awards: 13},
  { genre: 'Rock', band: 'Breaking Benjamins', albums: 1}
];

// function for dynamic sorting
function compareValues(key, order='asc') {
  return function(a, b) {
    if(!a.hasOwnProperty(key) || !b.hasOwnProperty(key)) {
      // property doesn't exist on either object
      return 0;
    }

    const varA = (typeof a[key] === 'string') ?
      a[key].toUpperCase() : a[key];
    const varB = (typeof b[key] === 'string') ?
      b[key].toUpperCase() : b[key];

    let comparison = 0;
    if (varA > varB) {
      comparison = 1;
    } else if (varA < varB) {
      comparison = -1;
    }
    return (
      (order == 'desc') ? (comparison * -1) : comparison
    );
  };
}


And this is how you’d use it:

// array is sorted by band, in ascending order by default
bands.sort(compareValues('band'));

// array is sorted by band in descending order
bands.sort(compareValues('band', 'desc'));

// array is sorted by albums in ascending order
bands.sort(compareValues('albums'));


Try it out

JS Bin on jsbin.com

In the code above, the hasOwnProperty method is used to check if the specified property is defined on each object and has not been inherited via the prototype chain. If it is not defined on the objects, the function returns 0, which causes the sort order to remain as is (i.e the objects remain unchanged with respect to each other).

The typeof operator is also used to check the data type of the value of the property. This allows the function to determine the proper way to sort the array. For example, if the value of the specified property is a string, a toUpperCase method is used to convert all its characters to uppercase, so character casing is ignored when sorting.

You can adjust the above function to accommodate other data types, and any other peculiarity your script needs.

String.prototype.localeCompare()

In our example above, we want to be able to sort an array of objects, whose values are either strings or numbers. If, however, you know that you will only be dealing with objects whose values are strings, you can tidy up the code a little using JavaScript’s localeCompare method.

This method returns a number indicating whether a string comes before, after, or is the same as a given string in the sort order. It enables a case-insensitive sort of an array:

["motorhead", "Motorhead", "Mötorhead"].sort();
// ["Motorhead", "Mötorhead", "motorhead"]

["motorhead", "Motorhead", "Mötorhead"].sort((a, b) => a.localeCompare(b));
//  ["motorhead", "Motorhead", "Mötorhead"]


In terms of our compareValues function, that means we could write:

function compareValues(key, order='asc') {
  return function(a, b) {
    if(!a.hasOwnProperty(key) || !b.hasOwnProperty(key)) return 0;
    let comparison = a[key].localeCompare(b[key]);

    return (
      (order == 'desc') ? (comparison * -1) : comparison
    );
  };
}


You can read more about localeCompare over on MDN.

Conclusion

So there you have it — a short introduction to sorting an array of objects. Although many JavaScript libraries offer this kind of dynamic sorting ability (e.g. Underscore.js, Lodash and Sugar), as demonstrated, it’s not all that hard to implement this kind of functionality yourself.

If you have any questions or comments, feel free to start a conversation.

*Originally published by Olayinka Omole at *https://www.sitepoint.com

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JavaScript Tutorial: if-else Statement in JavaScript

JavaScript Tutorial: if-else Statement in JavaScript

This JavaScript tutorial is a step by step guide on JavaScript If Else Statements. Learn how to use If Else in javascript and also JavaScript If Else Statements. if-else Statement in JavaScript. JavaScript's conditional statements: if; if-else; nested-if; if-else-if. These statements allow you to control the flow of your program's execution based upon conditions known only during run time.

Decision Making in programming is similar to decision making in real life. In programming also we face some situations where we want a certain block of code to be executed when some condition is fulfilled.
A programming language uses control statements to control the flow of execution of the program based on certain conditions. These are used to cause the flow of execution to advance and branch based on changes to the state of a program.

JavaScript’s conditional statements:

  • if
  • if-else
  • nested-if
  • if-else-if

These statements allow you to control the flow of your program’s execution based upon conditions known only during run time.

  • if: if statement is the most simple decision making statement. It is used to decide whether a certain statement or block of statements will be executed or not i.e if a certain condition is true then a block of statement is executed otherwise not.
    Syntax:
if(condition) 
{
   // Statements to execute if
   // condition is true
}

Here, condition after evaluation will be either true or false. if statement accepts boolean values – if the value is true then it will execute the block of statements under it.
If we do not provide the curly braces ‘{‘ and ‘}’ after if( condition ) then by default if statement will consider the immediate one statement to be inside its block. For example,

if(condition)
   statement1;
   statement2;

// Here if the condition is true, if block 
// will consider only statement1 to be inside 
// its block.

Flow chart:

Example:

<script type = "text/javaScript"> 

// JavaScript program to illustrate If statement 

var i = 10; 

if (i > 15) 
document.write("10 is less than 15"); 

// This statement will be executed 
// as if considers one statement by default 
document.write("I am Not in if"); 

< /script> 

Output:

I am Not in if
  • if-else: The if statement alone tells us that if a condition is true it will execute a block of statements and if the condition is false it won’t. But what if we want to do something else if the condition is false. Here comes the else statement. We can use the else statement with if statement to execute a block of code when the condition is false.
    Syntax:
if (condition)
{
    // Executes this block if
    // condition is true
}
else
{
    // Executes this block if
    // condition is false
}


Example:

<script type = "text/javaScript"> 

// JavaScript program to illustrate If-else statement 

var i = 10; 

if (i < 15) 
document.write("10 is less than 15"); 
else
document.write("I am Not in if"); 

< /script> 

Output:

i is smaller than 15
  • nested-if A nested if is an if statement that is the target of another if or else. Nested if statements means an if statement inside an if statement. Yes, JavaScript allows us to nest if statements within if statements. i.e, we can place an if statement inside another if statement.
    Syntax:
if (condition1) 
{
   // Executes when condition1 is true
   if (condition2) 
   {
      // Executes when condition2 is true
   }
}

Example:

<script type = "text/javaScript"> 

// JavaScript program to illustrate nested-if statement 

var i = 10; 

if (i == 10) { 

// First if statement 
if (i < 15) 
	document.write("i is smaller than 15"); 

// Nested - if statement 
// Will only be executed if statement above 
// it is true 
if (i < 12) 
	document.write("i is smaller than 12 too"); 
else
	document.write("i is greater than 15"); 
} 
< /script> 

Output:

i is smaller than 15
i is smaller than 12 too
  • if-else-if ladder Here, a user can decide among multiple options.The if statements are executed from the top down. As soon as one of the conditions controlling the if is true, the statement associated with that if is executed, and the rest of the ladder is bypassed. If none of the conditions is true, then the final else statement will be executed.
if (condition)
    statement;
else if (condition)
    statement;
.
.
else
    statement;


Example:

<script type = "text/javaScript"> 
// JavaScript program to illustrate nested-if statement 

var i = 20; 

if (i == 10) 
document.wrte("i is 10"); 
else if (i == 15) 
document.wrte("i is 15"); 
else if (i == 20) 
document.wrte("i is 20"); 
else
document.wrte("i is not present"); 
< /script> 

Output:

i is 20

How to Retrieve full Profile of LinkedIn User using Javascript

How to Retrieve full Profile of LinkedIn User using Javascript

I am trying to retrieve the full profile (especially job history and educational qualifications) of a linkedin user via the Javascript (Fetch LinkedIn Data Using JavaScript)

Here we are fetching LinkedIn data like Username, Email and other fields using JavaScript SDK.

Here we have 2 workarounds.

  1. Configuration of linkedIn developer api
  2. Javascript Code to fetch records

Configuration of linkedIn developer api

In order to fetch records, first we need to create developer api in linkedin which will act as token/identity while fetching data from other linkedin accounts.

So to create api, navigate to https://linkedin.com/developer/apps and click on 'Create Application'.

After navigating, fill in details like name, description and other required fields and then submit.

As we submit, it will create Client ID and Client Secret shown below, which we will be using in our code while communicating to fetch records from other LinkedIn account.

Note: We need to provide localhost Url here under Oauth 2.0. I am using my localhost, but you can probably use other production URLs under Oauth 2.0 where your app is configured. It will make your api  consider the Url as trusted which fetching records.

Javascript Code to fetch records

For getting user details like first name, last name,User image can be written as,

<script type="text/javascript" src="https://platform.linkedin.com/in.js">  
    api_key: XXXXXXX //Client ID  
    onLoad: OnLinkedInFrameworkLoad //Method that will be called on page load  
    authorize: true  
</script>  
<script type="text/javascript">  
    function OnLinkedInFrameworkLoad() {  
        IN.Event.on(IN, "auth", OnLinkedInAuth);  
    }  
  
    function OnLinkedInAuth() {  
        IN.API.Profile("me").result(ShowProfileData);  
    }  
  
    function ShowProfileData(profiles) {  
        var member = profiles.values[0];  
        var id = member.id;  
        var firstName = member.firstName;  
        var lastName = member.lastName;  
        var photo = member.pictureUrl;  
        var headline = member.headline;  
        //use information captured above  
        var stringToBind = "<p>First Name: " + firstName + " <p/><p> Last Name: " + lastName + "<p/><p>User ID: " + id + " and Head Line Provided: " + headline + "<p/>"  
        document.getElementById('profiles').innerHTML = stringToBind;  
    }  
</script>    

Kindly note we need to include 'https://platform.linkedin.com/in.js' as src under script type as it will act on this Javascript SDK provided by Linkedin.

In the same way we can also fetch records of any organization with the companyid as keyword.

<head>  
    <script type="text/javascript" src="https://platform.linkedin.com/in.js">  
        api_key: XXXXXXX ////Client ID  
        onLoad: onLinkedInLoad  
        authorize: true  
    </script>  
</head>  
  
<body>  
    <div id="displayUpdates"></div>  
    <script type="text/javascript">  
        function onLinkedInLoad() {  
            IN.Event.on(IN, "auth", onLinkedInAuth);  
            console.log("On auth");  
        }  
  
        function onLinkedInAuth() {  
            var cpnyID = XXXXX; //the Company ID for which we want updates  
            IN.API.Raw("/companies/" + cpnyID + "/updates?event-type=status-update&start=0&count=10&format=json").result(displayCompanyUpdates);  
            console.log("After auth");  
        }  
  
        function displayCompanyUpdates(result) {  
            var div = document.getElementById("displayUpdates");  
            var el = "<ul>";  
            var resValues = result.values;  
            for (var i in resValues) {  
                var share = resValues[i].updateContent.companyStatusUpdate.share;  
                var isContent = share.content;  
                var isTitled = isContent,  
                    isLinked = isContent,  
                    isDescription = isContent,  
                    isThumbnail = isContent,  
                    isComment = isContent;  
                if (isTitled) {  
                    var title = isContent.title;  
                } else {  
                    var title = "News headline";  
                }  
                var comment = share.comment;  
                if (isLinked) {  
                    var link = isContent.shortenedUrl;  
                } else {  
                    var link = "#";  
                }  
                if (isDescription) {  
                    var description = isContent.description;  
                } else {  
                    var description = "No description";  
                }  
                /* 
                if (isThumbnailz) { 
                var thumbnailUrl = isContent.thumbnailUrl; 
                } else { 
                var thumbnailUrl = "http://placehold.it/60x60"; 
                } 
                */  
                if (share) {  
                    var content = "<a target='_blank' href=" + link + ">" + comment + "</a><br>";  
                    //el += "<li><img src='" + thumbnailUrl + "' alt=''>" + content + "</li>";  
                    el += "<li><div>" + content + "</div></li>";  
                }  
                console.log(share);  
            }  
            el += "</ul>";  
            document.getElementById("displayUpdates").innerHTML = el;  
        }  
    </script>  
</body>  

We can get multiple metadata while fetching records for any any organization. We can get company updates as shown below.

Conclusion

We can also fetch any company specific data like company job updates/post, total likes, comments, and number of views along with a lot of metadata we can fetch which I have shown below.

Thank you for reading !

7 Best Javascript Iframe Libraries

7 Best Javascript Iframe Libraries

Iframes let you build user experiences into embeddable ‘cross-domain components’, which let users interact with other sites without being redirected. I have compiled 7 best Javascript iframe libraries.

Iframes let you build user experiences into embeddable ‘cross-domain components’, which let users interact with other sites without being redirected. I have compiled 7 best Javascript iframe libraries.

1. Zoid

A cross-domain component toolkit, supporting:

  • Render an iframe or popup on a different domain, and pass down props, including objects and functions
  • Call callbacks natively from the child window without worrying about post-messaging or cross-domain restrictions
  • Create and expose components to share functionality from your site to others!
  • Render your component directly as a React, Vue or Angular component!
    It's 'data-down, actions up' style components, but 100% cross-domain using iframes and popups!

Download


2. Postmate

Postmate is a promise-based API built on postMessage. It allows a parent page to speak with a child iFrame across origins with minimal effort.

Download


3. Iframe Resizer

Keep same and cross domain iFrames sized to their content with support for window/content resizing, in page links, nesting and multiple iFrames

Demo

Download


4. Iframely

Embed proxy. Supports over 1800 domains via custom parsers, oEmbed, Twitter Cards and Open Graph

Demo

Download


5. React Frame component

This component allows you to encapsulate your entire React application or per component in an iFrame.

Demo

Download


6. Seamless.js

A seamless iframe makes it so that visitors are unable to distinguish between content within the iframe and content beside the iframe. Seamless.js is a JavaScript library (with no dependencies) that makes working with iframes easy by doing all the seamless stuff for you automatically.

Demo

Download


7. Porthole

A proxy to safely communicate to cross-domain iframes in javascript

Demo

Download


Thank for read!