![]() What they are and how to use them by Gav Įver seen constants like _DIR_ and _FILE_ being used in PHP? These are 'Magic Constants', and this is how we can use them. Learn how to regenerate and update WordPress media and image sizes both programmatically (without plugin), and also with a handy plugin. Regenerate WordPress media image sizes, programmatically by Gav Measuring script/code execution time in PHP, microtime by Gav įind bottlenecks, optimise and clean your code, and speed up your apps by measuring the execution time of your PHP scripts using microtime. Use these methods in JavaScript to help optimise your code. Measuring code execution performance is an important way to identify bottlenecks. Measuring code execution performance in JavaScript by Gav Learn about Parsing and Writing YAML files using Symfony's YAML component. In this tutorial we will look at using YAML in PHP. Reading/Parsing and Writing YAML files, PHP Symfony by Gav Use Implements to implement interfaces and types, and extends to inherit from classes. Learn the difference between implements and extends in TypeScript. Implements and Extends, Object Oriented TypeScript by Gav Discover their benefits and best practices. Learn how to improve code readability and performance by using guard clauses in JavaScript. How to/why use guard clauses in JavaScript by Gav Learn how to create and register your own WordPress shortcodes to add dynamic content to your posts and pages. At this point we could also push the elements to an arrayĬreate, register and use shortcodes in WordPress by Gav ![]() const boxes = document.getElementsB圜lassName('box') From here we could loop our array-like object ‘as-is’ or push each iteration to a new array (in this case ‘boxArray’) for a future use. Last, but not least, you could solve this problem the good old fashioned way with a simple iterator loop. slice.call(document.getElementsB圜lassName('box')) Convert to array using an iterator loop var boxes = (document.getElementsB圜lassName('box')) Basically we are using the array method ‘ slice‘ (which returns a copy of an array) on an array-like object with a ‘call’ method, and then saving the copy into a new array object. slice.call for short) methods for converting. More widely supported, we can use the () (or. You should note that this method isn’t actually supported by Internet Explorer, but who cares about Internet Explorer now anyway… const boxes = om(document.getElementsB圜lassName('box')) Convert to array using () This is my preferred method of converting to array because it is semantically very easy to read at a glance. The code looks something like this: const boxArray = Convert to array using om()Īom does what it sounds like it converts array-like objects to actual arrays. This works because the HTMLCollection is iterable. Convert to array using a spread operatorĪ spread operator will allow us to expand the values of our array-like object and push them into a new array. Here are 4 ways to convert the returned HTMLCollection to an array. Ĭonst boxes = document.getElementsB圜lassName('box') Each div has the same class and we query for a HTMLCollection using ‘ getElementsB圜lassName‘. Let’s start with a simple scenario where we have 5 divs. Today I’m going to show you how to make these objects a little bit more useful, by converting them into JavaScript arrays. They include objects with a length property, such as HTMLCollection, NodeList, argument list and even strings. To fix the issue, you should use traditional functions as the method (function) of the object.Facebook Share Twitter Share LinkedIn ShareĮver had an array-like object that you want to iterate over? These annoying collections, which look like arrays, don’t have access to useful array methods like the ‘ forEach‘ loop. Therefore, the Javascript engine adds the numbers property to the window object and sets its value to undefined. ![]() However, objects in javascript do not have a lexical scope, therefore an arrow function will look outside (beyond) the object for the value of this, what is outside ? the global scope (window object) which does not have the numbers property. ![]() ![]() In the code above, the this keyword in arrow function should refer to properties and methods (function) of the printNumbers object. It uses the this value of the enclosing lexical scope. Please refer to my other tutorial to understand more about scope.Īn Arrow function doesn't have its own this value. There are two types of scope, Global and Local scope. In javascript, Scope refers to the current context of code, which determines the accessibility of variables to javascript. To understand what caused the error, we need to understand scope and arrow functions in javascript. Enter fullscreen mode Exit fullscreen mode ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |