How to update core-js to core-js@3 dependency?

You update core-js with the following command:

npm install --save core-js@^3

If you read the React Docs you will find that the command is derived from when you need to upgrade React itself.

For npm

 npm install --save core-js@^3

for yarn

yarn add core-js@^3

For ng9 upgraders:

npm i -g core-js@^3

..then:

npm cache clean -f

..followed by:

npm i

How about reinstalling the node module? Go to the root directory of the project and remove the current node modules and install again.

These are the commands : rm -rf node_modules npm install

OR

npm uninstall -g react-native-cli and

npm install -g react-native-cli