How to check if a value exists in an array in React JS?

In ReactJS, checking if a value exists in an array is a basic JavaScript operation. You can use the Array.prototype.includes() method or the Array.prototype.indexOf() method to accomplish this. Here’s how you can use each method:

Using Array.prototype.includes(): The includes() method returns a boolean indicating whether the array contains a specified value.

import React from 'react';

class ValueInArray extends React.Component {
  render() {
    const array = [1, 2, 3, 4, 5]; // Your array here
    const valueToCheck = 3; // The value you want to check

    const doesExist = array.includes(valueToCheck);

    return (
      <div>
        <p>Does Value Exist: {doesExist ? 'Yes' : 'No'}</p>
      </div>
    );
  }
}

export default ValueInArray;

Using Array.prototype.indexOf(): The indexOf() method returns the first index at which a given element can be found in the array, or -1 if the element is not present.

import React from 'react';

class ValueInArray extends React.Component {
  render() {
    const array = [1, 2, 3, 4, 5]; // Your array here
    const valueToCheck = 3; // The value you want to check

    const doesExist = array.indexOf(valueToCheck) !== -1;

    return (
      <div>
        <p>Does Value Exist: {doesExist ? 'Yes' : 'No'}</p>
      </div>
    );
  }
}

export default ValueInArray;

Both methods are valid, and you can choose the one that you find more readable or suitable for your specific use case. Note that the includes() method is more straightforward and is often preferred when you only need to check for the presence of a value in the array.