export-helper

export-helper

Pretentious name for a tiny nodejs module that edits the last line of a file.

Why ?

It basically turns export = myModule; into default export myModule; between tsc compilations (both ways supported)
Use it to compile into the syntax of Old (require(), NOT require().default) and a valid es6 module, in a single build command.

Compatibility

node >= 10

Install

npm install --save-dev export-helper

Use

Javascript file helper.js:

const exportHelper = require("export-helper");

exportHelper({ mode: "es6", path: "testFile.ts" })
  .then(res => res);

In terminal:

$ node helper.js
$ npmjs/export-helper: "export = constant;" has successfully be replaced by "export default constant;" (testFile.ts)

Options

This function accepts an option object :

const options = { 
  mode: "es6", // needed. Available options: "es5", "es6"
  path: "testFile.ts", // needed. Path to file (./ is optionnal)
  silent: false, // default to false; set to true to remove the log
  linesToTrim: 1 /* default to 1.
    You usually don't need this, but in case your IDE insert 
    an extra blank line between your module export and EOF, 
    incrementing that value should do the trick.
   */
};

... more examples ?

This is my configuration on the module I made this for.
I have an utility file updateExport.js:

const exportHelper = require("export-helper");

const updateExport = () => {
  if (process.argv.slice(2)[0] === "es5") {
    exportHelper({ mode: "es5", path: "src/index.ts" }).then((res) => res);
  } else if (process.argv.slice(2)[0] === "es6") {
    exportHelper({ mode: "es6", path: "src/index.ts" }).then((res) => res);
  } else
    throw "Oopsie, it seems you forgot to pass either 'es5' or 'es6' as argument !";
};

updateExport();

This is my npm run build script:
node rebuild.js && node updateExport.js es5 && tsc -p tsconfig-cjs.json && node updateExport.js es6 && tsc -p tsconfig.json

• rebuild.js is a simple utility that wipes the /lib folder before compilation.
• node updateExport.js es5: wrapping my module into a function using process.argv, I can easily pass arguments to it. Basically it will read the last line of my index file, search for default and replace it by =. It is that dumb.
• tsc -p tsconfig-cjs.json: I'm calling tsc with this config file
• Now that I've compiled a proper cjs version with module.exports, I call node updateExport.js es6 to change back the source code.
• Finally I call tsc to build the es6 module.