Is there a Webpack plugin available that can analyze the usage of a function exported in a static

Question

Is there a Webpack plugin available that can analyze the usage of a function exported in a static

Just to clarify, I am presenting this theoretical scenario on purpose, as it reflects a genuine issue that I need to solve and am uncertain if it's feasible.

Imagine I have a JavaScript package named road-fetcher, containing a function called find which accepts a lat/lng coordinate and returns the nearest road to that location.

For instance:

import { find } from 'road-fetcher'

find(36.585940, -95.304241) // output: 'US Route 66'

Assume that a user of my road-fetcher application uses this find function around 200-300 times in their web app (all in predictable, non-random ways).

Internally, my road-fetcher package makes network requests to my external API. Although it currently functions well, repeatedly doing this at runtime results in unnecessary bandwidth and latency costs for each client, whether in the browser or server. Furthermore, all 200 calls may occur on the same webpage. To optimize this, it would be preferable to precompute values at build time and possibly establish a long TTL to update values later on.

It is common practice to process JavaScript using Webpack, so I am contemplating if it is viable to statically analyze a user's utilization of the find function to identify all possible combinations.

Ideally, I aim to compile a comprehensive list of function calls with their arguments and then initiate a network request based on this information during the build phase. However, even compiling a list of all argument combinations and storing it somewhere in the filesystem (possibly within node_modules or current working directory) to facilitate a single cache-warming step would suffice.

Upon initial examination of the Webpack documentation, it appears that evaluateCallExpressionMember could serve as a starting point, although I may be facing challenges beyond my expertise.

I acknowledge that this example may seem artificial, but it mirrors a real dilemma I am attempting to streamline in order to address the core problem effectively.

javascript node.js webpack optimization static-analysis

Answer 1

Answer №1

I successfully developed a webpack plugin that can handle a function name and a callback which will be executed with the arguments passed to the original function.

For those who want to dive straight into the code, check out the repository

The functionality has some limitations:

It is only compatible with ES modules
If a named import is renamed (e.g.,
```
import { log as logg } from './something'
```
), it will not work
It cannot handle function arguments that are variables

Outcome

This snippet showcases my source code:

import { log } from './helpers/log';

// logs displayed
log(1);
log(2, 3);
log(2, "foo");
log(2, "foo", 4, "bar");
log(2, "foo", 4, "bar", [1, 2, "asd"]);
log(2, "foo", 4, "bar", [1, 2, "asd"], { foo: "bar" }, [
  { a: "asd", b: 123, c: [] },
]);

// not logged due to variable usage
const a = [1,2,3];
log(a);

// also not logged because it does not use `log`
console.log('asd');

Here's the webpack configuration:

const FunctionCallPlugin = require('./webpack-plugins/FunctionCall');

module.exports = {
  plugins: [ new FunctionCallPlugin({ functionName: 'log', callback: ({ arguments: args }) => {
    console.log('`log` function was found and called with the arguments:', args);
    // actions like HTTP requests or database writes can be added here
  }})],
}

When running webpack, you'll see these outputs in the terminal:

➜  webpack-plugin-function-invoke git:(master) ✗ yarn webpack
yarn run v1.16.0
warning ..\package.json: No license field
$ D:\Projects\webpack-plugin-function-invoke\node_modules\.bin\webpack
`log` function was found and called with the arguments: [ 1 ]
`log` function was found and called with the arguments: [ 2, 3 ]
`log` function was found and called with the arguments: [ 2, 'foo' ]
`log` function was found and called with the arguments: [ 2, 'foo', 4, 'bar' ]
`log` function was found and called with the arguments: [ 2, 'foo', 4, 'bar', [ 1, 2, 'asd' ] ]
`log` function was found and called with the arguments: [
  2,
  'foo',
  4,
  { foo: 'bar' },
  [ { a: 'asd', b: 123, c: [] } ]
]

Functioning of the Plugin

All webpack chunks and modules within them are scanned to identify dependencies with the specified name (e.g., log)
Paths to the original source files containing these dependencies are gathered via fileDependencies
The content of each file is read as a string using the fs module
Babel parser is used to convert the source code into an AST
Traversing the AST helps identify all instances of CallExpression involving the specified function name
Arguments passed in every function call are collected
The designated callback function is executed with the compiled arguments

That sums up the process! It may not be the most efficient, but it definitely gets the job done :)

If you're curious about the code, feel free to explore the GitHub repository. While this may not cover everything, I hope it sheds some light on your query!

Answer 2

I successfully developed a webpack plugin that can handle a function name and a callback which will be executed with the arguments passed to the original function.

For those who want to dive straight into the code, check out the repository

The functionality has some limitations:

It is only compatible with ES modules
If a named import is renamed (e.g.,
```
import { log as logg } from './something'
```
), it will not work
It cannot handle function arguments that are variables

Outcome

This snippet showcases my source code:

import { log } from './helpers/log';

// logs displayed
log(1);
log(2, 3);
log(2, "foo");
log(2, "foo", 4, "bar");
log(2, "foo", 4, "bar", [1, 2, "asd"]);
log(2, "foo", 4, "bar", [1, 2, "asd"], { foo: "bar" }, [
  { a: "asd", b: 123, c: [] },
]);

// not logged due to variable usage
const a = [1,2,3];
log(a);

// also not logged because it does not use `log`
console.log('asd');

Here's the webpack configuration:

const FunctionCallPlugin = require('./webpack-plugins/FunctionCall');

module.exports = {
  plugins: [ new FunctionCallPlugin({ functionName: 'log', callback: ({ arguments: args }) => {
    console.log('`log` function was found and called with the arguments:', args);
    // actions like HTTP requests or database writes can be added here
  }})],
}

When running webpack, you'll see these outputs in the terminal:

➜  webpack-plugin-function-invoke git:(master) ✗ yarn webpack
yarn run v1.16.0
warning ..\package.json: No license field
$ D:\Projects\webpack-plugin-function-invoke\node_modules\.bin\webpack
`log` function was found and called with the arguments: [ 1 ]
`log` function was found and called with the arguments: [ 2, 3 ]
`log` function was found and called with the arguments: [ 2, 'foo' ]
`log` function was found and called with the arguments: [ 2, 'foo', 4, 'bar' ]
`log` function was found and called with the arguments: [ 2, 'foo', 4, 'bar', [ 1, 2, 'asd' ] ]
`log` function was found and called with the arguments: [
  2,
  'foo',
  4,
  { foo: 'bar' },
  [ { a: 'asd', b: 123, c: [] } ]
]

Functioning of the Plugin

All webpack chunks and modules within them are scanned to identify dependencies with the specified name (e.g., log)
Paths to the original source files containing these dependencies are gathered via fileDependencies
The content of each file is read as a string using the fs module
Babel parser is used to convert the source code into an AST
Traversing the AST helps identify all instances of CallExpression involving the specified function name
Arguments passed in every function call are collected
The designated callback function is executed with the compiled arguments

That sums up the process! It may not be the most efficient, but it definitely gets the job done :)

If you're curious about the code, feel free to explore the GitHub repository. While this may not cover everything, I hope it sheds some light on your query!

Is there a Webpack plugin available that can analyze the usage of a function exported in a static

Answer №1

Outcome

Functioning of the Plugin

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