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npm install --save-dev @babel/helpers



import * as helpers from "@babel/helpers";
import * as t from "@babel/types";

const typeofHelper = helpers.get("typeof");

// true

Inside a plugin:

export default {
visitor: {
UnaryExpression(path) {
// The .addHelper function adds, if needed, the helper to the file
// and returns an expression which references the helper
const typeofHelper = this.addHelper("typeof");
t.isExpression(typeofHelper); // true

Defining Helpers

NOTE: This package is only meant to be used by the packages included in this repository. There is currently no way for third-party plugins to define a helper.

Helpers are defined in the src/helpers.js file, and they must be valid modules which follow these guidelines:

  • They must have a default export, which is their entry-point.
  • They can import other helpers, exclusively by using default imports.
  • They can't have named exports.
helpers.customHelper = defineHelper(`
import dep from "dependency";

const foo = 2;

export default function getFooTimesDepPlusX(x) {
return foo * dep() + x;