ms.macro/src/ms.macro.js

Convert various time formats to milliseconds at build time in Babel.

import { createMacro, MacroError } from 'babel-plugin-macros';
import ms from 'ms';

const getValue = (path) => {
  if (path.type === 'CallExpression') {
    return path.node.arguments[0].value;
  }
  if (path.type === 'TaggedTemplateExpression') {
    return path.node.quasi.quasis[0].value.cooked;
  }
  return null;
};

export default createMacro(({ babel: { types: t }, references: { default: paths } }) => {
  paths.forEach(({ parentPath }) => {
    const value = getValue(parentPath);
    if (value) {
      const newValue = ms(value);
      if (newValue) {
        parentPath.replaceWith(t.numericLiteral(newValue));
      } else {
        const { line } = parentPath.node.loc.start;
        throw new MacroError(`Invalid input given to ms.macro at line ${line}`);
      }
    }
  });
});