if !ArrayisArraylist return ; return listmapitem = itemsignatoriesmapi = spanisignatoryNamespan 当signatoryName的值一样则显示一个就可以

You can achieve this by using the filter method to remove duplicate signatory names before mapping them. Here's an updated version of the code:

if (!Array.isArray(list)) return '';
return list.map((item) => {
  const uniqueSignatories = item.signatories.filter((signatory, index, array) => {
    return array.findIndex((s) => s.signatoryName === signatory.signatoryName) === index;
  });

  return uniqueSignatories.map((signatory) => (
    <span>{signatory?.signatoryName}</span>
  ));
});

This code filters out duplicate signatory names using the filter method along with the findIndex method. The findIndex method checks if the current signatory's name has already been encountered before in the array. If it hasn't, it returns the current index, indicating that it is the first occurrence. Only the signatories with unique names are then mapped and returned as a list of <span> elements.