Category: React Answers

Sometimes, we want to set the content of an iframe of a React component.

In this article, we’ll look at how to set the content of an iframe of a React component.

Set the Content of an Iframe of a React Component

To set the content of an iframe of a React component, we can set the srcDoc prop of the iframe element.

For instance, we can write:

import React from "react";

export default function App() {
  const myHTML = `<h1>Hello World</h1>`;
  return (
    <div>
      <iframe srcDoc={myHTML} title="hello" />
    </div>
  );
}

to set the srcDoc prop to the HTML string that we want to display as the iframe’s content.

Therefore, we should see ‘Hello World’ displayed inside the iframe.

Conclusion

To set the content of an iframe of a React component, we can set the srcDoc prop of the iframe element.

Sometimes, we want to get the HTML5 input slider working in React.

In this article, we’ll look at how to get the HTML5 input slider working in React.

Get the HTML5 Input Slider Working in React

To get the HTML5 input slider working in React, we either set the value and onChange props or we can leave them both out.

For instance, we can write:

import React, { useState } from "react";

export default function App() {
  const [value, setValue] = useState(0);

  return (
    <input
      type="range"
      min="0"
      max="5"
      value={value}
      onChange={(e) => setValue(e.target.value)}
      step="1"
    />
  );
}

We add the value prop and set it to the value state.

And we set the onChange prop to a function that calls setValue with e.target.value , which has the selected number value.

This makes the range slider a controlled component which means its value is controlled by a state.

We can also leave them both out if we don’t want to bind the value of the range slider to a state.

This would make it an uncontrolled input.

Conclusion

To get the HTML5 input slider working in React, we either set the value and onChange props or we can leave them both out.

Sometimes, we want to format code with the pre tag in React and JSX.

In this article, we’ll look at how to format code with the pre tag in React and JSX.

Format Code with the pre Tag in React and JSX

To format code with the pre tag in React and JSX, we should put the code we want to display in template literals.

For instance, we can write:

import React from "react";

export default function App() {
  const foo = 1;
  const bar = '"a b   c"';

  return (
    <pre>{`
    var foo = ${foo};
    var bar = ${bar};
  `}</pre>
  );
}

We interpolate the foo and bar strings in the code template string.

All the spaces in the template string are preserved.

Conclusion

To format code with the pre tag in React and JSX, we should put the code we want to display in template literals.

Sometimes, we want to edit the value of multiple controlled input components in React.

In this article, we’ll look at how to edit the value of multiple controlled input components in React.

Edit Multiple Controlled Input Components’ Values in React

To edit the value of multiple controlled input components in React, we can create a function that returns the onChange callback for each input.

For instance, we can write:

import React, { useState } from "react";

export default function App() {
  const [contact, setContact] = useState({ firstName: "", lastName: "" });

  const handleChange = (propertyName) => (event) =>
    setContact((c) => ({ ...c, [propertyName]: event.target.value }));

  return (
    <div>
      <input
        type="text"
        onChange={handleChange("firstName")}
        value={contact.firstName}
      />
      <input
        type="text"
        onChange={handleChange("lastName")}
        value={contact.lastName}
      />
    </div>
  );
}

We have the contact state which is set to an object with the firstName and lastName properties as its initial value.

Then we create the handleChange function that takes propertyName and calls setContact to update the contact state’s propertyName property with the inputted value, which is stored in e.target.value .

Then we have 2 inputs with the value props set to each contact property.

And the onChange props are set to functions returned by handleChange with the propertyName to set the contact ‘s firstName or lastName property depending on the field.

Conclusion

To edit the value of multiple controlled input components in React, we can create a function that returns the onChange callback for each input.

Sometimes, we want to send multipart form data with Axios in a React component.

In this article, we’ll look at how to send multipart form data with Axios in a React component.

Send Multipart Form Data with Axios in a React Component

We can send form data with the FormData constructor.

We can pass that straight into the Axios post method.

For instance, we can write:

import React from 'react'
import axios, { post } from 'axios';

class App extends React.Component {

  constructor(props) {
    super(props);
    this.state ={
      file:null
    }
    this.onFormSubmit = this.onFormSubmit.bind(this)
    this.onChange = this.onChange.bind(this)
    this.fileUpload = this.fileUpload.bind(this)
  }

  onFormSubmit(e){
    e.preventDefault()
    const url = 'http://example.com/upload';
    const formData = new FormData();
    formData.append('file', this.state.file);
    const config = {
      headers: {
        'content-type': 'multipart/form-data'
      }
    }
    post(url, formData, config);
      .then((response) => {
        console.log(response.data);
      })
  }

  onChange(e) {
    this.setState({ file: e.target.files[0 ]})
  }

  render() {
    return (
      <form onSubmit={this.onFormSubmit}>
        <h1>File Upload</h1>
        <input type="file" onChange={this.onChange} />
        <button type="submit">Upload</button>
      </form>
   )
  }
}

We have a file input, where we set the file input to the file that’s submitted in the onChange method.

We save the selected file object as the value of the file state.

Then when we click the Upload button, onFormSubmit is run.

In the method, we created a FomrData instance.

Then we append our file into the FormData instance.

We also set the header so that we indicate that we’re sending form data.

Once we did that, we proceed with our file upload.

Conclusion

We can send form data with the FormData constructor.

We can pass that straight into the Axios post method.