React State From the Ground Up

#ReactJS State From the Ground Up #JavaScript

  • State, in React, is a plain JavaScript object that allows you keep track of a component’s data.
  • The initial state of the App component has been set to a state object which contains the key username, and its value using .
  • Initializing a component state can get as complex as what you can see here: – – An initialized state can be accessed in the method, as I did above.
  • Your component should look like this; – – A state can be passed as props from a parent to the child component.
  • This method will be used to update the state of the component.

As you begin to learn React, you will be faced with understanding what state is. State is hugely important in React, and perhaps a big reason you’ve looked into using React in the first place. Let’s take a stab at understanding what state is and how it works. What is State? State, in React, is a plain JavaScript
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React Tutorial: A Comprehensive Guide to learning React.js in 2018

  • These components are defined either in pure JavaScript or they can be defined in what the React team calls “JSX”.
  • The reason the React team went with this approach is because, since the virtual DOM is a JavaScript representation of the actual DOM, React can keep track of the difference between the current virtual DOM(computed after some data changes), with the previous virtual DOM (computed befores some data changes).
  • In more layman’s terms, because manipulating the actual DOM is slow, React is able to minimize manipulations to the actual DOM by keeping track of a virtual DOM and only updating the real DOM when necessary and with only the necessary changes.
  • The process looks something like this, – – Some user event which changes the state of your app → Re-render virtual DOM -> Diff previous virtual DOM with new virtual DOM -> Only update real DOM with necessary changes.
  • Signal to notify our app some data has changed→ Re-render virtual DOM -> Diff previous virtual DOM with new virtual DOM -> Only update real DOM with necessary changes.

Continue reading “React Tutorial: A Comprehensive Guide to learning React.js in 2018”

React Tutorial: A Comprehensive Guide to learning React.js in 2018

  • These components are defined either in pure JavaScript or they can be defined in what the React team calls “JSX”.
  • The reason the React team went with this approach is because, since the virtual DOM is a JavaScript representation of the actual DOM, React can keep track of the difference between the current virtual DOM(computed after some data changes), with the previous virtual DOM (computed befores some data changes).
  • In more layman’s terms, because manipulating the actual DOM is slow, React is able to minimize manipulations to the actual DOM by keeping track of a virtual DOM and only updating the real DOM when necessary and with only the necessary changes.
  • The process looks something like this, – – Some user event which changes the state of your app → Re-render virtual DOM -> Diff previous virtual DOM with new virtual DOM -> Only update real DOM with necessary changes.
  • Signal to notify our app some data has changed→ Re-render virtual DOM -> Diff previous virtual DOM with new virtual DOM -> Only update real DOM with necessary changes.

Continue reading “React Tutorial: A Comprehensive Guide to learning React.js in 2018”

7 Ways To Define A Component Template in VueJS – JS Dojo – Medium

7 Ways To Define A Component Template in #VueJS:  by @getjsdojo #JavaScript #ReactJS

  • X-TemplatesWith this method your template is defined inside a script tag in the index.html file.
  • Th script tag is marked with text/x-template and referenced by an id in your component definition.I like that this method allows you to write your HTML in proper HTML markup, but the downside is that it separate the template from the rest of the component definition.4.
  • It suffers the same downside as x-templates, but one advantage is that content is in the correct place within the HTML template and so can be rendered on page load rather than waiting until Javascript is run.5.
  • Single File ComponentsSo long as you are comfortable with using a build tool in your setup, Single File Components are the king of template options.
  • They bring the best of both worlds: allowing you to write markup while keeping all your component defintion in one file.They require transpiling and some IDEs don’t support syntax highlighting for this file type, but are otherwise hard to beat.You might argue there are even more template definition possibilities since you can use template pre-processors like Pug with SFCs!Which is the best?Of course there’s no one perfect way, and each should be judged on the use case you have.

There’s plenty of choice when it comes to defining component templates in Vue. By my count there are at least seven different ways: In this article we’ll go through examples of each and address the…
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Using Props in React – ziv zamechek – Medium

Using Props in React  #javascript #react #reactjs

  • In between the time it takes the first render of the component to fetching this data and setting it on our state that takes some time and during that time the length of videos is equal to 0 that is the reason that we see 0 for half a second when refreshing the page.
  • this.state = { videos: [] };When it is first rendered it does search of surfboards and it gets the response from this.stateApp is the parent of video list and video list need to get access to the videos that are in the app state.
  • passing data from the parent component App to the child component VideoList we are passing the list of videos just by defining a property on the JSX tag.Here we are passing video list to render method.
  • Anytime when App re render VideoList will get the videos as well.So now we have a functional VideoList component and it has array of videos to render.
  • Our video list component will receive props that contain an array of videos so we just loop over this array and for each video will generate one instance of video list for each item.Now each VideoListItem which is intended to show a single video now it will show a single li with a video.A map is a built in method that is a property of an array.

When we use functional component the props object will arrive as an argument to the function. const videos = props.videos; this is the array of videos. {props.videos.length} so this is saying that…
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Putting the “Native” in React Native

Putting the

  • Thankfully, getting the system volume is not difficult in iOS or Android, so it makes a perfect example of a simple native module.
  • This post will walk through making a native module for iOS, for Android, and the JavaScript code we can use in our app to call our new modules.
  • In our React Native module, we have a bit of a special case: we need only define the module in our header file as each method we want to expose is done so via the macro in the implementation file only.
  • Just as we did with the iOS module, we can add a method to our module that will get the system’s volume (see this commit in our example code).
  • We’ll need to use the to get the system volume, so add a couple imports to :

    And add an instance variable set in the constructor:

    Adding the actual method looks similar to the iOS version:

    One final improvement we can do is refactor our use of into its own JavaScript module, (see this commit in our example code):

    Then, we can get the volume using:

    A benefit of this refactoring is that if we want to perform different native code depending on the platform, we can isolate those code branches to their own (testable!)

A guide to writing native modules in a React Native application.
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Why I like Vue over React – Munawwar – Medium

  • i. trigger state change through props + listen to componentWillReceiveProps(), which can then change the internal state of the child component
  • Vue.js gives an easy way to access child components using “ref” attribute on the component’s custom element.
  • 3. Attaching events to component root element: When it comes to parent component listening to events on a child, I prefer to attach anonymous functions as event handlers to the root element of the child.
  • Vue.js, gives ability to directly attach an event handler by defining a “v-on:eventname.native” attribute on the component’s custom element.
  • [A gotcha is that $refs isn’t available until the component renders.

As a person who have spent time writing his own JS framework, I am nitpicky, when it come to frameworks. When it comes to React, there are several things I don’t like, which Vue.js seems to have…
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