virtual-dom | A simple virtual DOM implementation

Well, the reason for The client-side rendered virtual DOM tree is not matching server-rendered content is probably the use of randomness - more specifically the usage of getRandomString function in the NewsList.vue component to generate unique ID's

As @kissu pointed out in his answer

any random is risky

new Date() inside NewsListItem.vue will cause problem too as the resuting Date object will be different on server and the client causing client side VDom difference from the HTML generated by server...

I solved your issue, the fixed blog can be seen here
https://brians-spare-time-blog.netlify.app/interests/film-photography/

In your Sidebar.vue file you do have

You are mutating the original images array.

You set newImages = images (which is just a reference not a copy) and then change positions in newImages.

That effectively changes the original array, and so when react compares the newImages you pass to setImages with the previous images they are the same array and so, no change is detected.

You can fix it with let newImages = [...images];

Virtual DOM is just a javascript object in memory. While DOM is also mainly in memory (no in disk and on the cloud), it's a complex system with many parts connected.

The difference is that DOM is slow. Manipulating DOM involves many other tasks (https://stackoverflow.com/a/6817110/8810271). Manipulating a virtual DOM without other tasks is no more than a javascript object, which is much faster than element.innerHTML=x.

But remember you still need to manipulate DOM after diffing virtual DOM, to make changes take effect. And it isn't always faster.

The key here is that Demo is not unmounted. When you first render the app, it renders and mounts the Demo component and passes the onChange prop. But, when the callback is invoked from Demo it sets the state on App. Calling setState in App doesn't unmount the Demo component, so there's no need to mount it again. When the component is mounted initially is when the constructor runs. If you had a toggle on the App component that would only show the component within render if a certain condition is true, that would trigger the component to unmount.

Check out this codesandbox and play around a little: https://codesandbox.io/s/lifecycle-methods-vivn6?file=/src/Lifecycle.js.

Also, this is a cool diagram to get a sense of what's happening: https://projects.wojtekmaj.pl/react-lifecycle-methods-diagram/

The main key is that the constructor runs when the component mounts. It will only run again if the component is unMounted from the DOM and then remounted later.

Since the error message says set platform to "node" when building for node, I assume that since you didn't do that this means you are bundling for the browser, not for node. The events package is built in to node but it is not built in to the browser.

It looks like parcel-bundler depends on node-libs-browser which depends on crypto-browserify which depends on events. This explains why installing Parcel fixes this error. If your project needs to depend on the events package (https://www.npmjs.com/package/events), you should install it yourself so it's part of your project:

Template should only contain 1 element thats fine. But you should not loop the top parent element. Try to wrap it in an div

You can't use class with React because React uses React DOM, which uses camelCase property names, not classical HTML attributes. This is why in JSX (React render language), you have to use className, not class.

Vue is using classical HTML template, so class is allowed.

With Svelte, you should be able to use class keyword in your template.