Comparison
BundlervsHot module replacement
Bundler
you point one tool at an entry file and it follows every import and writes out a handful of files.
A build tool that resolves the module graph from an entry point and emits the files a browser downloads, applying transforms along the way. It exists because thousands of small modules over the network is slower than a few large files, and because most of what you write is not directly runnable in a browser. Its configuration is where resolution, transpilation, splitting and asset handling all meet, which is why bundler config is the part of a project nobody wants to own.
Full entry →Hot module replacement
you saved the file and the component updated on screen without losing what you had typed into the form.
Swapping a changed module into the running application without a full reload, preserving state where it can. It is the main reason dev servers exist as separate machinery from the production build. It is also a source of confusing behaviour: state that survives a hot update can hide a bug that a real load would expose, so anything odd deserves a hard refresh before it is investigated.
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