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by Arooj Ahmed via Digital Information World
Wednesday, October 28, 2020
Study shows which gaming companies are using the influencer-marketing strategy the most
CreatorIQ, an influencer-marketing platform, analyzed thousands of sponsored posts from creators and influencers to discover which brands were appearing most in sponsored ads. CreatorIQ examined two thousand seven hundred posts from one hundred and eighty creators and influencers from last month...
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by Arooj Ahmed via Digital Information World
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by Arooj Ahmed via Digital Information World
The Best Software for Live Streaming on YouTube
Back in 2016, researchers laid out a prediction that the Live Streaming industry would be worth $70 billion by 2021. Interestingly, they didn’t take into account the coronavirus outbreak, something that encouraged a considerable portion of the human population to resort to live streaming for the...
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by Ali Siddiqui via Digital Information World
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by Ali Siddiqui via Digital Information World
During the year 2020, the rate of online shopping apps have increased by 40%
The coronavirus pandemic has locked everyone in their homes. People have no other things except for using social media and as all types of shopping malls are closed people are engaged in online shopping. They are shopping more than usual as they have no other source of entertainment and no other...
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by Arooj Ahmed via Digital Information World
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by Arooj Ahmed via Digital Information World
Working with Forms in React
Almost every application needs to accept user input at some point, and this is usually achieved with the venerable HTML form and its collection of input controls. If you’ve recently started learning React, you’ve probably arrived at the point where you’re now thinking, “So how do I work with forms?”
This article will walk you through the basics of using forms in React to allow users to add or edit information. We’ll look at two different ways of working with input controls and the pros and cons of each. We’ll also take a look at how to handle validation, and some third-party libraries for more advanced use cases.
Uncontrolled Inputs
The most basic way of working with forms in React is to use what are referred to as “uncontrolled” form inputs. What this means is that React doesn’t track the input’s state. HTML input elements naturally keep track of their own state as part of the DOM, and so when the form is submitted we have to read the values from the DOM elements themselves.
In order to do this, React allows us to create a “ref” (reference) to associate with an element, giving access to the underlying DOM node. Let’s see how to do this:
class SimpleForm extends React.Component {
constructor(props) {
super(props);
// create a ref to store the DOM element
this.nameEl = React.createRef();
this.handleSubmit = this.handleSubmit.bind(this);
}
handleSubmit(e) {
e.preventDefault();
alert(this.nameEl.current.value);
}
render() {
return (
<form onSubmit={this.handleSubmit}>
<label>Name:
<input type="text" ref={this.nameEl} />
</label>
<input type="submit" name="Submit" />
</form>
)
}
}
As you can see above, for a class-based component you initialize a new ref in the constructor by calling React.createRef, assigning it to an instance property so it’s available for the lifetime of the component.
In order to associate the ref with an input, it’s passed to the element as the special ref attribute. Once this is done, the input’s underlying DOM node can be accessed via this.nameEl.current.
Let’s see how this looks in a functional component:
function SimpleForm(props) {
const nameEl = React.useRef(null);
const handleSubmit = e => {
e.preventDefault();
alert(nameEl.current.value);
};
return (
<form onSubmit={handleSubmit}>
<label>Name:
<input type="text" ref={nameEl} />
</label>
<input type="submit" name="Submit" />
</form>
);
}
There’s not a lot of difference here, other than swapping out createRef for the useRef hook.
Example: login form
function LoginForm(props) {
const nameEl = React.useRef(null);
const passwordEl = React.useRef(null);
const rememberMeEl = React.useRef(null);
const handleSubmit = e => {
e.preventDefault();
const data = {
username: nameEl.current.value,
password: passwordEl.current.value,
rememberMe: rememberMeEl.current.checked,
}
// Submit form details to login endpoint etc.
// ...
};
return (
<form onSubmit={handleSubmit}>
<input type="text" placeholder="username" ref={nameEl} />
<input type="password" placeholder="password" ref={passwordEl} />
<label>
<input type="checkbox" ref={rememberMeEl} />
Remember me
</label>
<button type="submit" className="myButton">Login</button>
</form>
);
}
While uncontrolled inputs work fine for quick and simple forms, they do have some drawbacks. As you might have noticed from the code above, we have to read the value from the input element whenever we want it. This means we can’t provide instant validation on the field as the user types, nor can we do things like enforce a custom input format, conditionally show or hide form elements, or disable/enable the submit button.
Fortunately, there’s a more sophisticated way to handle inputs in React.
Controlled Inputs
An input is said to be “controlled” when React is responsible for maintaining and setting its state. The state is kept in sync with the input’s value, meaning that changing the input will update the state, and updating the state will change the input.
Let’s see what that looks like with an example:
class ControlledInput extends React.Component {
constructor(props) {
super(props);
this.state = { name: '' };
this.handleInput = this.handleInput.bind(this);
}
handleInput(event) {
this.setState({
name: event.target.value
});
}
render() {
return (
<input type="text" value={this.state.name} onChange={this.handleInput} />
);
}
}
As you can see, we set up a kind of circular data flow: state to input value, on change event to state, and back again. This loop allows us a lot of control over the input, as we can react to changes to the value on the fly. Because of this, controlled inputs don’t suffer from the limitations of uncontrolled ones, opening up the follow possibilities:
- instant input validation: we can give the user instant feedback without having to wait for them to submit the form (e.g. if their password is not complex enough)
- instant input formatting: we can add proper separators to currency inputs, or grouping to phone numbers on the fly
- conditionally disable form submission: we can enable the submit button after certain criteria are met (e.g. the user consented to the terms and conditions)
- dynamically generate new inputs: we can add additional inputs to a form based on the user’s previous input (e.g. adding details of additional people on a hotel booking)
Validation
As I mentioned above, the continuous update loop of controlled components makes it possible to perform continuous validation on inputs as the user types. A handler attached to an input’s onChange event will be fired on every keystroke, allowing you to instantly validate or format the value.
Continue reading Working with Forms in React on SitePoint.
by Nilson Jacques via SitePoint
An ultimate guide to grid design
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Security Researchers Highlight 17 Android Gaming Apps on Google Play Store That Can Bombard Users With Ads
After receiving a report from the Czech antivirus company, Avast, about twenty-one apps that were infected with codes of adware, Google (so far) decided to take down eighteen of those apps that were consistently reported for showing irrelevant ads (while 3 of them are still available in the Play...
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by Arooj Ahmed via Digital Information World
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by Arooj Ahmed via Digital Information World
YouTube App Gets Upgraded With Gesture Controls and Playback Options
YouTube is really trying to emphasize the fact that users would want to use their app on mobile phones and it is trying to make the smartphone YouTube viewing experience much better than might have been the case otherwise by adding lots of new features to try and meet this end. Some of the new...
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by Zia Muhammad via Digital Information World
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by Zia Muhammad via Digital Information World
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