@atlaskit/eslint-plugin-design-system/dist/es2019/rules/ensure-design-token-usage/em-to-pixels.js

The essential plugin for use with the Atlassian Design System.

const emRegex = /(.*\d+)em$/;
const percentageRegex = /(%$)/;
export const emToPixels = (value, fontSize) => {
  if (typeof value === 'string') {
    const emMatch = value.match(emRegex);
    if (emMatch && typeof fontSize === 'number') {
      return Number(emMatch[1]) * fontSize;
    } else if (value.match(percentageRegex)) {
      return value;
    } else {
      return null;
    }
  }
  return value;
};