src/language-js/print/jsx.js/printJsxAttribute
function printJsxAttribute(path, options, print) {
  const node = path.getValue();
  const parts = [];
  parts.push(print("name"));

  if (node.value) {
    let res;
    if (isStringLiteral(node.value)) {
      const raw = rawText(node.value);
      // Remove enclosing quotes and unescape
      // all quotes so we get an accurate preferred quote
      let final = raw
        .slice(1, -1)
        .replace(/&apos;/g, "'")
        .replace(/&quot;/g, '"');
      const { escaped, quote, regex } = getPreferredQuote(
        final,
        options.jsxSingleQuote ? "'" : '"'
      );
      final = final.replace(regex, escaped);
      res = [quote, final, quote];
    } else {
      res = print("value");
    }
    parts.push("=", res);
  }

  return parts;
}