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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

how to install exact package lock version in package-lock.json

"npm ci" command, which will install the exact versions listed in package-lock. json "npm i" command install the version-ranges given in package

npm what package-lock.json is for

cases                                | npm install | npm ci
 --------------------------------------|-------------|-------------
  needs package.json                   | no          | yes
  needs package-lock.json              | no          | yes
  installs from package.json           | yes         | no
  installs from package-lock.json      | no          | yes
  compares both                        | no          | yes
  updates loose package versions       | yes         | no
  updates loose dependencies           | yes         | no
  writes to package.json               | yes         | no
  writes to package-lock.json          | yes         | no
  deletes node_modules before install  | no          | yes
  used for installing separate package | yes         | no
  should be used on build systems / CI | no          | yes
  can be used for development          | yes         | yes
  reproducible installs                | no          | yes