React-Native: Convert image url to base64 string

Question

I'm building a react native app that needs to store images at base64 string format for offline viewing capabilities.

What library / function would give me the best result to store the image as base64 string? assuming my url is "http://www.example.com/image.png".

Also, do I need to make http request to get it before storing it as a string? my logic says yes, but in react native you can load images on the <Image> component without request them first from the server.

What would be the best option to do this in react native?

Answer 1

I use rn-fetch-blob, basically it provides lot of file system and network functions make transferring data pretty easy.

react-native-fetch-blob is deprecated

import RNFetchBlob from "rn-fetch-blob";
const fs = RNFetchBlob.fs;
let imagePath = null;
RNFetchBlob.config({
  fileCache: true
})
  .fetch("GET", "http://www.example.com/image.png")
  // the image is now dowloaded to device's storage
  .then(resp => {
    // the image path you can use it directly with Image component
    imagePath = resp.path();
    return resp.readFile("base64");
  })
  .then(base64Data => {
    // here's base64 encoded image
    console.log(base64Data);
    // remove the file from storage
    return fs.unlink(imagePath);
  });

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