Function isCustomComponent

code/event-handlers/public/app.js:14488–14509

(tagName, props)

}

function isCustomComponent(tagName, props) {
  if (tagName.indexOf('-') === -1) {
    return typeof props.is === 'string';
  }
  switch (tagName) {
    // These are reserved SVG and MathML elements.
    // We don't mind this whitelist too much because we expect it to never grow.
    // The alternative is to track the namespace in a few places which is convoluted.
    // https://w3c.github.io/webcomponents/spec/custom/#custom-elements-core-concepts
    case 'annotation-xml':
    case 'color-profile':
    case 'font-face':
    case 'font-face-src':
    case 'font-face-uri':
    case 'font-face-format':
    case 'font-face-name':
    case 'missing-glyph':
      return false;
    default:
      return true;
  }
}

// When adding attributes to the HTML or SVG whitelist, be sure to
// also add them to this module to ensure casing and incorrect name