Today I finally learnt once and for all the difference between tilde(~) and caret(^) in package.json. Until now, I was never sure what the exact difference is. So here is the explanation.
The tilde(~) matches the most recent minor version. This means that for a version number such as 1.2.x, the 2 will never be changed, and only the last digit x will be updated to the newest version of that NPM module.
The principle for caret(^) is the same except that it's slightly looser and will match any major version. So in a package with version numbe 1.y.x, both y and x will be updated. But if the package comes with the version 2.0.0, the caret(^) symbol will be of no help here and will not update to 2.0.0.
Based on the article "npm install --save" No Longer Using Tildes by Fred K. Schott.