Explain benefits of a lockfile

In a JavaScript application run through a package manager such as npm or yarn, what is the role of a dependency lockfile (for example, package-lock.json or yarn.lock)? Describe the main benefits it provides in local development and CI/CD, and the problems it helps prevent.

Overview: Assesses a candidate's grasp of dependency management and reproducible builds in JavaScript package ecosystems, and how package managers coordinate project dependencies.