How to optimize webpack's build time using prefetchPlugin & analyse tool?

Solution 1:

Yeah, The pre-fetch plugin documentation is pretty much non-existent. After figuring it out for myself, its pretty simple to use, and there's not much flexibility to it. Basically, it takes two arguments, the context (optional) and the module path (relative to context). The context in your case would be /absolute/path/to/your/project/node_modules/react-transform-har/ assuming that the tilde in your screenshot is referring to node_modules as per webpack's node_module resolution.

The actual prefetch module should be ideally no more than three module dependencies deep. So in your case isFunction.js is the module with the long build chain and ideally it should be pre-fetched at getNative.js

However, I suspect there's something funky in your config, because your build chain dependencies are referring to module dependencies, which should be automatically optimized by webpack. I'm not sure how you got that, but in our case, we don't see any warnings about long build chains in node_modules. Most of our long build chains are due to deeply nested react components which require scss. ie:

Regardless, you'll want to add a new plugin for each of the warnings, like so:

plugins: [
    new webpack.PrefetchPlugin('/web/', 'app/modules/HeaderNav.jsx'),
    new webpack.PrefetchPlugin('/web/', 'app/pages/FrontPage.jsx')
];

The second argument must be a string to the relative location of the module. Hope this makes sense.

Solution 2:

The middle of your chain there is probably react-transform-hmr/index.js as it starts about half way through. You could try PrefetchPlugin('react-transform-hmr/index') and rerun your profile to see if it helps speed up your total time to build.