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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 setting up the basic infra, rather focus on building the application.
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 looking for an element with id test, you can use the following −const elem = document.querySelector('#test'); console.log(document.body.contains(elem));This will log true or false based on whether the element is present in the visible DOM.
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 = new Date(); console.log(date.addDays(1));This will log the next day.
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 value. For example −Example// Search the select box const mySelectBox = document.querySelector('#my-select'); // Set the value to 3 or Strawberry mySelectBox.value = 3;
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 = 100; function fnWeWantToHide(x, y) { return (x + y) * HIDDEN_CONST } console.log(fnWeWantToHide(1, 2))If we write the above code out in the open this code will pollute the global namespace with these names. Instead what we can do is wrap this in an IIFE(immediately invoked functional expressions). For ... Read More
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 own pros and cons. Let's look at some of those.Pros −Allows applications to render without data and fill data as the application gets it from the server.Gives platform independence to application developersFaster page rendersMore responsive applicationsNo rerenders of whole pages are needed to update only a single area.Cons−Any user whose ... Read More
You can use lodash's set method to set properties at any level safely. Setting first-level properties are pretty straightforward. Nested property access is tricky and you should use a tested library like lodash for it.You can set a deeply nested object in the following way −Examplelet _ = require("lodash"); let obj = { a: { b: { foo: "test" }, c: 2 } }; _.set(obj, "a.b.foo", "test1"); _.set(obj, "a.c", { test2: "bar" }); console.log(obj);OutputThis will give the output −{ a: { b: { foo: 'test1' ... Read More
You can use lodash's get method to get properties at any level safely. Getting first-level properties is pretty straightforward. Nested property access is tricky and you should use a tested library like lodash for it.You can access a deeply nested object in the following way −Examplelet _ = require("lodash"); let obj = { a: { b: { foo: "test" }, c: 2 } }; console.log(_.get(obj, "a.b.foo")); console.log(_.get(obj, "a.c")); console.log(_.get(obj, "a.test")); console.log(_.get(obj, "a.test.x"));OutputThis will give the output −test 2 undefined undefinedYou can also write your own ... Read More
You can use lodash's get method to get properties at any level safely. Getting first-level properties is pretty straightforward. Nested property access is tricky and you should use a tested library like lodash for it.You can access a deeply nested object in the following way −Examplelet _ = require("lodash"); let obj = { a: { b: { foo: "test" }, c: 2 } }; console.log(_.get(obj, "a.b.foo")); console.log(_.get(obj, "a.c")); console.log(_.get(obj, "a.test")); console.log(_.get(obj, "a.test.x"));OutputThis will give the output −test 2 undefined undefinedYou can also write your own ... Read More
JavaScript can send network requests to the server and load JSON. JS does this using something called AJAX. AJAX stands for Asynchronous JavaScript and XML. JS has an API, fetch, to GET(receive) and POST(send) information to the server.You can use fetch to GET JSON data in the following way −Exampleconst URL = 'https://jsonplaceholder.typicode.com/todos/1' // Send a GET request without any data to the server fetch(URL, {method: "GET"}) // Get the JSON data from the raw response .then(res => res.json()) // Print the result .then(console.log)OutputThis will give the output −{ "userId": 1, "id": 1, "title": "delectus ... Read More