what is use of package-lock.json code example

Example 1: npm generate package-lock.json

npm install --package-lock

Example 2: how to generate package-lock.json from package.json

Have you deleted package-lock.json file? don't worry 
Run below command to generate package-lock.json file in your folder.

npm i --package-lock-only

Example 3: package-lock what is it

The package-lock.json is solely used to lock dependencies to a 
 specific version number.  So that when teammates clone your work 
 their dependency versions are the same as yours, or vice versa.