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Javascript Articles
Page 523 of 534
Increment a date in javascript without using any libraries?
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.
Read MoreHow to programmatically set the value of a select box element using JavaScript?
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;
Read MoreJavaScript Encapsulation using Anonymous Functions
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 MoreSafely setting object properties with dot notation strings in JavaScript
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 MoreSafely Accessing Deeply Nested Values In JavaScript
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 MoreQuery-string encoding of a Javascript Object
The query string is made up of query parameters and used to send data to the server. This part of the URL is optional. It needs to be constructed by the developer. This can be done using a native method called encodeURIComponent.The encodeURIComponent() function encodes a Uniform Resource Identifier (URI) component by replacing each instance of certain characters by one, two, three, or four escape sequences representing the UTF-8 encoding of the characterUsing the new ES6 format, objects can be query string encoded in the following way −Examplelet obj = { name: 'John', age: 25, city: 'Chicago' ...
Read MoreWhat are the differences between lodash and underscore?
lodash and underscore are both utility libraries that make JavaScript easier by providing utils that make working with arrays, numbers, objects, strings, etc. much easier. These libraries are great for −Iterating arrays, objects, & stringsManipulating & testing valuesCreating composite functionsThey are both functional libraries. Lo-Dash is a fork of Underscore, and still follows Underscore’s API enough to allow it to serve as a drop-in replacement. But under the hood, it’s been completely rewritten, and it’s also added a number of features and functions that Underscore does not provide.Lo-Dash was created to provide more consistent cross-environment iteration support for arrays, strings, ...
Read MoreWrite the dependencies of backbone.js in javascript?
The only hard dependency(without which backbone js won't work at all) is Underscore.js. Underscore is a JavaScript library that provides a whole mess of useful functional programming helpers without extending any built-in objects.There are other dependencies required as you proceed to use more advanced features of backbone.js. For example,Libraries for RESTful persistence(Backbone.sync)History support via Backbone.RouterDOM manipulation with Backbone.View or Jquery
Read MoreWhat is JSlint error "missing radix parameter" in JavaScript?
The parseInt function available in JavaScript has the following signature −parseInt(string, radix);Where the parameters are the following −string − The value to parse. If this argument is not a string, then it is converted to one using the ToString method. Leading whitespace in this argument is ignored.radix − An integer between 2 and 36 that represents the radix (the base in mathematical numeral systems) of the string.If the radix parameter is omitted, JavaScript assumes the following −If the string begins with "0x", the radix is 16 (hexadecimal)If the string begins with "0", the radix is 8 (octal). This feature is ...
Read MoreWhat is the difference between `new Object()` and object literal notation in JavaScript?
Both new Object() notation and Object literal({}) notations do the same thing. They initialize an object. However, the second notation can be a little different if you start adding properties to it.Examplelet a = { name: 'Ayush' }This initialization is equivalent to −let a = new Object(); a.name = 'Ayush'orlet a = {} a.name = 'Ayush'
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