replace-method

replace-method

JavaScript post-processing step to replace specific function/method calls with other bits of JavaScript. It doesn't take scope into account, but is otherwise a good starting point for writing your own inlinifying transform modules like brfs.

Usage

replace = require('replace-method')(ast)

Returns a function you can use to replace methods with other things.

Where ast is either a string of source code, or an AST object such as one generated by esprima.

replace(method, found)

Where method is an array of variable names, such that:

• ['__filename'] will match __filename.
• ['fs', 'readFileSync'] will match fs.readFileSync.
• ['a', 'nested', 'property'] will match a.nested.property.

found is then called once per every node in the AST found – if you return nothing or undefined, nothing will change. However, if you return an AST object that content will be replaced, e.g.:

return {
  type: 'Literal',
  value: 'hello world'
}

Will replace the matched variable with the string "hello world".

replace.code()

Returns the updated version of your code after having made the transformations you needed. Note that the supplied ast object you provided will be modified directly so you can convert it to JavaScript yourself or hand it off to other processing steps if need be.

Example

var replaceMethod  = require('replace-method')
var evaluate       = require('static-eval')
var escodegen      = require('escodegen')
var esprima        = require('esprima')
var fs             = require('fs')

var src = replaceMethod(
  fs.readFileSync(__filename, 'utf8')
)

src.replace(['fs', 'readFileSync'], function(node) {
  if (!node.arguments.length) return

  var filename = evaluate(node.arguments[0], {
      __filename: __filename
    , __dirname:  __dirname
  })

  if (filename) return {
      type: 'Literal'
    , value: fs.readFileSync(filename, 'utf8')
  }
})

console.log(src.code())

License

MIT. See LICENSE.md for details.