計算內部二維數組的值 - javascript

Question

我有一個二維數組。 我正在嘗試計算內部數組中的值。 我知道 JS array.length 。 但是做testData.length會產生 5。這是准確的。 但是，我想計算每個子數組中的項目數。

testData[0].length將產生 6。但是我將如何動態計算每個子數組？ （因為它會改變）。

var testData = [["column1","test1","test1","tea","party", "water bottle"],
                ["column2","test2","test2","test2 test2"],
                ["column3","test2","test2","test2 test2 "],
                ["column4","test2","test2 test2f asdfsdf"],
                ["column5","test2","test2 test2f asdfsdfasdfasdfasa asda asdfsas"]
]

Answer 1

使用reduce ：

ES6：

const count = testData.reduce((currentCount, row) => currentCount + row.length, 0);

ES5：

var count = testData.reduce(function(currentCount, row) { 
    return currentCount + row.length;
}, 0);

文檔： https ://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/Reduce

Answer 2

使用Array.forEach

s=0;
testData.forEach(function(e,i,a){s += e.length; });

另請參閱： https ://developer.mozilla.org/en-US/docs/JavaScript/Reference/Global_Objects/Array/forEach

Answer 3

var testData = [
    ["column1","test1","test1","tea","party", "water bottle"],
    ["column2","test2","test2","test2 test2"],
    ["column3","test2","test2","test2 test2 "],
    ["column4","test2","test2 test2f asdfsdf"],
    ["column5","test2","test2 test2f asdfsdfasdfasdfasa asda asdfsas"]
];
for(var i=0;i < testData.length;i++){
  for(var j=0;j<testData[i].length;j++){
    alert(testData[i][j]);
  }
}

Answer 4

嘗試向 Array 對象添加新屬性。

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <meta http-equiv="content-type" content="text/html; charset=windows-1250">
    <title>New Property</title>
    <script type="text/javascript" language="JavaScript">
      Array.prototype.biLength = function(){
        numItems = 0;
        numRows = this.length;
        for (var i = 0; i < numRows; i++){
          row = testData[i];
          numCols = row.length;
          for (var j = 0; j < numCols; j++){
            numItems++;
          }
        }
        return numItems;
      };
      var testData = [
        ["column1","test1","test1","tea","party", "water bottle"],
        ["column2","test2","test2","test2 test2"],
        ["column3","test2","test2","test2 test2 "],
        ["column4","test2","test2 test2f asdfsdf"],
        ["column5","test2","test2 test2f asdfsdfasdfasdfasa asda asdfsas"]
      ];
      alert(testData.biLength());
    </script>
  </head>
  <body>

  </body>
</html>

計算內部二維數組的值 - javascript

問題描述

4 個解決方案

解決方案1
11 2018-01-26 21:27:57

解決方案2
5 2013-05-09 18:09:52

解決方案3
0 已采納 2013-05-09 18:07:18

解決方案4
0 2013-05-09 18:17:52

計算內部二維數組的值 - javascript

問題描述

4 個解決方案

解決方案1 11 2018-01-26 21:27:57

解決方案2 5 2013-05-09 18:09:52

解決方案3 0 已采納 2013-05-09 18:07:18

解決方案4 0 2013-05-09 18:17:52

解決方案1
11 2018-01-26 21:27:57

解決方案2
5 2013-05-09 18:09:52

解決方案3
0 已采納 2013-05-09 18:07:18

解決方案4
0 2013-05-09 18:17:52