localStorage and sessionStorage in JavaScript

In JavaScript, there are 2 ways to store data within a web browser: localStorage, which can be used to save data across browser sessions sessionStorage, which stores data for the page session localStorage localStorage.setItem(‘examplevariable’, ‘123’); var a = localStorage.getItem(“examplevariable”); console.log(a); This prints: To delete a variable, we use: localStorage.removeItem(‘examplevariable’); If we try to access the variable after deleting, it will return null. If we set the item in localStorage and … Continue reading localStorage and sessionStorage in JavaScript

jQuery Introduction and Hello World

jQuery is a popular JavaScript library that is very useful with JavaScript development. It contains many benefits and features, including: It’s cross-browser It has selectors It works with events Ajax support 3rd party plugins from developers To install, go to https://jquery.com/ and select the version you would like to download: If you need support for Internet Explorer versions 6-8, Opera 12.1x, or Safari 5.1x you will need jQuery 1.x. Otherwise, you … Continue reading jQuery Introduction and Hello World

Compare Dates in JavaScript

In JavaScript, there are ways to compare dates as well as methods that will not work. For example, if we have: var date1 = new Date(“2018-01-01 00:00”); var date2 = new Date(“2018-01-01 00:00”); if (date1 == date2) console.log(“equal”) else console.log(“not equal”) This will print: If we print both dates to the console, we will see they are exactly the same (note the date is different from what was supplied – … Continue reading Compare Dates in JavaScript

JavaScript Dates – new Date and UTC

In JavaScript, we can create a new date using: var date1 = new Date(“2018-01-01″); If we print this in the console, we actually get a different date: This is because we are omitting the time, so UTC time is assumed. To display the “correct” date, add the time: var date1 = new Date(“2018-01-01 00:00”); This produces:    

JavaScript – Scroll to Top

In a scenario where we need to scroll to the top of a web page, we can use JavaScript’s scrollTo. Consider the scenario where there is a page filled with text, and the scroll bar appears. With a scroll button at the bottom: We can add the following code to set the window to it’s x/y coordinates: window.scrollTo(0,0); Full code: When clicking the button, the page will scroll to the … Continue reading JavaScript – Scroll to Top

JavaScript Async / Await

In some previous posts, we looked at using callbacks and promises. In this post, we will look at Await / Async in JavaScript. Await / Async is built on promises, and is a clean way to represent asynchronous processes in a synchronous way. For example, consider the code below. We have 2 functions, DoSomethingAsync and DoSomethingElseAsync.  The first function will complete in 2 seconds, and the second function in 1 second: If … Continue reading JavaScript Async / Await

Dynamics CRM Creating and Debugging JavaScript Code

One of the benefits of using Dynamics CRM is the ability to write client side JavaScript code to perform actions on the user interface. Let’s go through an example of how to do this. In this example, we will show a message box when a user changes a value on a field. We will do this on the Website field on the Accounts form: Firstly, edit the Accounts form to display the developer view: … Continue reading Dynamics CRM Creating and Debugging JavaScript Code

Node.js Hello World on Windows

In this example, we will create a Hello World application for Node.js. Let’s start with a simple example. I have installed Node.js on Windows and have a Node directory in C:\ drive. In command prompt, cd to this directory. In that directory is a JavaScript file that writes out a console log “Hello World”: To run the file, enter: node HelloWorld.js Hello World is returned by Node. Now create a new … Continue reading Node.js Hello World on Windows

D3 Hello World

To create a D3 “Hello World”, do the following. Go to the d3js.org website and find the latest D3 version: Copy the link to the latest release: <script src=”https://d3js.org/d3.v4.min.js”></script> Create an HTML page and add the following code, with the link above: <!DOCTYPE html> <meta charset=”utf-8″> <body> <script src=”https://d3js.org/d3.v4.min.js”></script> <script> d3.select(“body”).append(“span”) .text(“Hello world”); </script> Run the page: