Edit in JSFiddle

const data = {
  "dcids": [
    "SquareMeter1238495"
  ]
}
const request = new XMLHttpRequest();
const squareMeter1238495 = "SquareMeter1238495"
request.open("POST", "https://api.datacommons.org/node/triples", false /* async */ );
request.send(JSON.stringify(data));

if (request.status == 200) {
  let payload = JSON.parse(request.responseText)["payload"];
  let result = JSON.parse(payload);
  console.log(result);
  for (let i = 0; i < result[squareMeter1238495].length; i++) {
    let objectName = result[squareMeter1238495][i]["objectName"];
    let objectId = result[squareMeter1238495][i]["objectId"];
    let objectOutput = objectName ? objectName : objectId;
    
    let predicate = result[squareMeter1238495][i]["predicate"];
    
    let subjectName = result[squareMeter1238495][i]["subjectName"];
    let subjectId = result[squareMeter1238495][i]["subjectId"];
    let subjectOutput = subjectName ? subjectName : subjectId;
    
    document.write("subject: " + subjectOutput + "<br>");
    document.write("predicate: " + predicate + "<br>");
    document.write("object: " + objectOutput + "<br>");
    document.write("<br>")
  }

} else {
  console.log("There was an error fetching data.");
}

<h1>
Triples associated with SquareMeter 1238495
</h1>