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我正在尝试编写一个函数，该函数在 JSON 数组中找到最大值，然后从找到最大值的数组中返回另一个值。具体来说：找到具有最高（即最近）创建时间的表，然后返回该表的 id。该函数应返回“clickup-test-example:ClickUp_Teams.ClickUp_Teams_1619170399502”

{
    "totalItems": 3,
    "kind": "bigquery#tableList",
    "etag": "PCARXzLSMg+ycECbmPnMDQ==",
    "tables": [
      {
        "kind": "bigquery#table",
        "id": "clickup-test-example:ClickUp_Teams.ClickUp_Teams_1618403016322",
        "tableReference": {
          "projectId": "clickup-test-example",
          "datasetId": "ClickUp_Teams",
          "tableId": "ClickUp_Teams_1618403016322"
        },
        "type": "TABLE",
        "creationTime": "1618403016433",
        "expirationTime": "1623587016433"
      },
      {
        "kind": "bigquery#table",
        "id": "clickup-test-example:ClickUp_Teams.ClickUp_Teams_1619168558388",
        "tableReference": {
          "projectId": "clickup-test-example",
          "datasetId": "ClickUp_Teams",
          "tableId": "ClickUp_Teams_1619168558388"
        },
        "type": "TABLE",
        "creationTime": "1619168558487",
        "expirationTime": "1624352558487"
      },
      {
        "kind": "bigquery#table",
        "id": "clickup-test-example:ClickUp_Teams.ClickUp_Teams_1619170399502",
        "tableReference": {
          "projectId": "clickup-test-example",
          "datasetId": "ClickUp_Teams",
          "tableId": "ClickUp_Teams_1619170399502"
        },
        "type": "TABLE",
        "creationTime": "1619170399591",
        "expirationTime": "1624354399591"
      }
    ]
}

我尝试基于这两个线程编写此函数： Getting max value(s) in JSON array 和 Finding the max value of an attribute in an array of objects，但我不知道如何编写 Math.max 函数。任何其他解决方案也将不胜感激。提前致谢！

function findNewestTables() {
  const tables = BigQuery.Tables.list('clickup-test-307314','ClickUp_Teams'); // returns the JSON file above
  const newestTables = Math.max(tables.tables.map(function(o) { 
    return o.id;
    }));

  console.log(tables);
  console.log(newestTables);

};
4

3 回答 3

1

您可以在单独的变量中跟踪maxSoFar和，以及何时更改，.idmaxSoFarid

// Gets the original JSON, and declares the variables
const data = getData();
let
  maxSoFar = 0,
  id = "";

// Updates the variables whenever a newer item is found
data.tables.forEach(table => {
  const time = parseInt(table.creationTime);
  if(time > maxSoFar){
    maxSoFar = time; 
    id = table.id;
  }
});
// Logs the result
console.log(id);

// Provides the original JSON
function getData(){
  return {
    "tables": [
      { "id": "Teams_1618403016322", "creationTime": "1618403016433" },
      { "id": "Teams_1619168558388", "creationTime": "1619168558487" },
      { "id": "Teams_1619170399502", "creationTime": "1619170399591" }
    ]
  }
}

于 2021-04-23T19:16:15.197 回答
1

可能有一种巧妙的方法可以作为单线执行此操作，但也许……</p> 

function findMostRecent(json) {
  const times = json.tables.map(table => table.creationTime);
  const maxValue = Math.max(...times);
  const mostRecent = x.tables.find(table => table.creationTime === maxValue);
  
  return most.recent.id
}
于 2021-04-23T19:02:01.823 回答
1

解决此问题的一种方法是遍历表，搜索具有最大创建时间的表，然后返回属于该表的 ID。

这是一个粗略实现的示例：


const findBiggestInTable = (tables) => {
  const largest = tables[0];
  for (int i = 0; i < tables.length; i++) {
    if (tables[i].creationTime > largest.creationTime) {
        largest = tables[i];
    }
  }

  return largest.id;
}
于 2021-04-23T19:03:21.750 回答