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useMemo,useLocation from react

useMemo and useLocation are two distinct hooks in the React ecosystem, serving different purposes.

useMemo (from react)
useMemo is a React Hook that allows for memoization of a value. This means it caches the result of an expensive calculation and only re-runs the calculation if its dependencies change. This can significantly improve performance by preventing unnecessary re-calculations on every render. 

import React, { useMemo } from 'react';

function MyComponent({ data }) {
  // Expensive calculation that only re-runs if 'data' changes
  const processedData = useMemo(() => {
    // Perform complex data processing here
    return data.map(item => item.value * 2);
  }, [data]); // Dependencies array

  return (
    <div>
      {/* Render processedData */}
      {processedData.map((item, index) => (
        <p key={index}>{item}</p>
      ))}
    </div>
  );
}

useLocation (from react-router-dom)

useLocation is a hook provided by the react-router-dom library, not directly from react. It allows you to access the current URL's location object, which contains information about the current route. This information includes pathname, search (query parameters), hash, and state (data passed during navigation). 

import React from 'react';
import { useLocation } from 'react-router-dom';

function CurrentRouteInfo() {
  const location = useLocation();

  return (
    <div>
      <p>Pathname: {location.pathname}</p>
      <p>Search Query: {location.search}</p>
      <p>Hash: {location.hash}</p>
      {/* Access state data if available */}
      {location.state && <p>State Data: {JSON.stringify(location.state)}</p>}
    </div>
  );
}
Key Differences: 
  • Origin:
    useMemo is a core React hook, while useLocation is part of react-router-dom.
  • Purpose:
    useMemo optimizes performance by memoizing values, while useLocation provides access to route information.
  • Dependencies:
    useMemo takes a dependencies array to determine when to re-calculate, while useLocation automatically updates when the URL changes
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