MyComponent.js

const TEMPLATE = [
  '<div class="MyComponent @classes" @attributes>',
  '  <p>',
  '    @message',
  '  </p>',
  '</div>'
].join('\n').concat('\n')

const defaultParams = {
  classes: '',
  attributes: '',
  message: ''
}

export function render (params) {
  params = Object.assign({}, defaultParams, params)
  
  if (params.attributes) {
    params.attributes = Object.keys(params.attributes)
      .reduce((html, key) => {
        return html + `${key}="${params.attributes[key}"`
      }, '')
  }
  
  return TEMPLATE
    .replace('classes', params.classes)
    .replace('attributes', params.attributes)
    .replace('message', params.message)
}