Ayush Gupta has Published 527 Articles

How to terminate javascript forEach()?

Ayush Gupta

Ayush Gupta

Updated on 27-Nov-2019 12:17:48

548 Views

You can't break from the forEach method and it doesn't provide to escape the loop (other than throwing an exception).You can use other functions like _.find from lodash instead −_.find − it breaks out of the loop when the element is found. For example, Example_.find([1, 2, 3, 4], (element) => ... Read More

Most efficient method to groupby on an array of objects in Javascript

Ayush Gupta

Ayush Gupta

Updated on 27-Nov-2019 10:48:44

7K+ Views

The most efficient method to group by a key on an array of objects in js is to use the reduce function.The reduce() method executes a reducer function (that you provide) on each element of the array, resulting in a single output value.Exampleconst people = [    { name: 'Lee', ... Read More

How can I trigger an onchange event manually in javascript?

Ayush Gupta

Ayush Gupta

Updated on 27-Nov-2019 10:46:10

28K+ Views

You can dispatch events on individual elements using the dispatchEvent method. Let's say you have an element test with an onChange event −Event handler −document.querySelector('#test').addEventListener('change', () => console.log("Changed!"))Triggering the event manually −const e = new Event("change"); const element = document.querySelector('#test') element.dispatchEvent(e);This will log the following −Changed!Read More

How to delete a localStorage item when the browser window/tab is closed?

Ayush Gupta

Ayush Gupta

Updated on 27-Nov-2019 10:44:59

2K+ Views

To clear a localStorage data on browser close, you can use the window.onunload event to check for tab close.Let's say you have a local storage object called MyStorage as a global for the sake of this example. Then you can write an event handler −Examplewindow.onunload = () => {   ... Read More

Difference between MEAN.js and MEAN.io?

Ayush Gupta

Ayush Gupta

Updated on 27-Nov-2019 10:43:50

109 Views

MEAN is an acronym for MongoDB, Express, Angular, and Node.js.MEAN.js and MEAN.io are the same things essentially as they both are scaffolded applications or a basic set up to use the above 4 things. These libraries/tools have these set up for you already.These allow you to not spend time on ... Read More

How to check if element exists in the visible DOM?

Ayush Gupta

Ayush Gupta

Updated on 27-Nov-2019 10:42:43

776 Views

We can use the Node.contains method to do this check. The Node.contains() method returns a Boolean value indicating whether a node is a descendant of a given node, i.e. the node itself, one of its direct children (childNodes), one of the children's direct children, and so on.ExampleFor example, you are ... Read More

Increment a date in javascript without using any libraries?

Ayush Gupta

Ayush Gupta

Updated on 27-Nov-2019 10:41:22

184 Views

To add one day to date in JS, the setDate function is the best way. You can create the following function on the Date prototype to add days to the date.ExampleDate.prototype.addDays = function(days) {    let d = new Date(this.valueOf());    d.setDate(d.getDate() + days);    return d; } let date ... Read More

How to programmatically set the value of a select box element using JavaScript?

Ayush Gupta

Ayush Gupta

Updated on 27-Nov-2019 10:39:19

995 Views

We can set the value of a select box using Javascript using the following. Suppose we have the following select box −    Select    Apple    Strawberry    Cherry    Guava To set the value of this select element, we need to access it using querySelector. Then set the ... Read More

JavaScript Encapsulation using Anonymous Functions

Ayush Gupta

Ayush Gupta

Updated on 27-Nov-2019 10:37:08

433 Views

Object-oriented programming languages allow data hiding using private fields. They use these to hide the internals of classes. In JS there is no such in build support to hide/encapsulate the inner workings.We have Anonymous functions that can give you encapsulation in JS. Let us look at an example −Exampleconst HIDDEN_CONST ... Read More

The Pros and Cons of Using Ajax

Ayush Gupta

Ayush Gupta

Updated on 27-Nov-2019 10:35:33

6K+ Views

Ajax is a set of web development techniques using many web technologies on the client-side to create asynchronous web applications. With Ajax, web applications can send and retrieve data from a server asynchronously without interfering with the display and behavior of the existing page.Any other technology Ajax also has its ... Read More

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