farm-plugin-static-opt

Static optimization plugin for FarmFE — performs compile-time optimizations that JS engines would otherwise do at runtime.

Install

npm install farm-plugin-static-opt

Dependencies: This plugin uses core-ast-ts internally. Installed automatically.

Concept

This is not minification. This is compile-time static optimization — doing at build time what JS engines do at runtime:

• Constant folding: 2 + 3 → 5, "hello" + " world" → "hello world"
• Dead branch elimination: if (true) { A } else { B } → A
• Loop unrolling: for (let i = 0; i < 3; i++) { ... } → body × 3

This makes the output code smaller and faster before any minifier even sees it.

Usage

import staticOpt from 'farm-plugin-static-opt'

export default {
  plugins: [staticOpt()],
}

With options:

staticOpt({
  constantFolding: true,      // fold 2+3 → 5 (default: true)
  deadBranchElimination: true, // remove if(false) branches (default: true)
  loopUnrolling: true,         // unroll small loops (default: true)
  maxUnroll: 8,                // max trip count for unrolling (default: 8)
})

Optimizations

Constant Folding

Arithmetic, logical, and bitwise expressions with all-literal operands are evaluated at compile time:

// Before
const area = 3.14 * 4 * 4
const flag = true && false
const mask = 0xFF & 0x0F

// After
const area = 50.24
const flag = false
const mask = 15

String concatenation:

// Before
const url = "/api" + "/v1" + "/users"

// After
const url = "/api/v1/users"

Dead Branch Elimination

If/else and ternary with constant conditions:

// Before
if (true) {
  setupApp()
} else {
  setupFallback()
}

// After
setupApp()

// Before
const mode = false ? 'production' : 'development'

// After
const mode = 'development'

Works especially well combined with farm-plugin-selective — after selective compilation replaces conditions with literals, this plugin eliminates the dead branches.

Loop Unrolling

For-loops with known bounds and small trip counts:

// Before
for (let i = 0; i < 3; i++) {
  console.log(i)
}

// After
{
  console.log(0)
  console.log(1)
  console.log(2)
}

With step:

// Before
for (let i = 0; i < 6; i += 2) {
  process(i)
}

// After
{
  process(0)
  process(2)
  process(4)
}

Only unrolls loops with:

• Literal start, end, and step values
• Trip count ≤ maxUnroll (default: 8)
• Simple i++/i--/i += N/i -= N update

HMR

Optimizations are re-applied on file changes.

License

MIT