Count values of the inner two-dimensional array - javascript

Question

I have a two-dimensional array. I'm trying to count the values within the inner array. I'm aware of JS array.length. But doing testData.length yields 5. Which is accurate. However, I want to count the number of items within each sub array.

testData[0].length would yield 6. But how would I dynamically count through each sub array? (as it will change).

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"]
]

Prayag Sagar · Accepted Answer · 2022-06-23 06:14:30Z

12

Use 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);

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

edited Jun 23, 2022 at 6:14

Prayag Sagar

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answered Jan 26, 2018 at 21:27

Sascha Klatt

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Comments

Lu Wang · Accepted Answer · 2013-05-09 18:09:52Z

5

Use Array.forEach

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

See also: https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Global_Objects/Array/forEach

answered May 9, 2013 at 18:09

Lu Wang

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Comments

웃웃웃웃웃 · Accepted Answer · 2018-12-20 06:54:00Z

0

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]);
  }
}

edited Dec 20, 2018 at 6:54

answered May 9, 2013 at 18:07

웃웃웃웃웃

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1 Comment

EnigmaRM Over a year ago

Your inner for loop is counting the actual characters within the sub array isn't it? Definitely don't need to go that far. I instead moved console.log(testData[i].length); to the first loop. And it achieves correct results. Thanks.

Marco Muciño · Accepted Answer · 2013-05-09 18:17:52Z

Try adding a new property to the Array object.

<!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>

Mark Rotteveel · Accepted Answer · 2024-11-26 12:29:53Z

0

var lengths = testData.map(subArray => subArray.length);
console.log(lengths);

edited Nov 26, 2024 at 12:29

Mark Rotteveel

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answered Nov 26, 2024 at 5:54

Mahesh Shinde

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1 Comment

Mark Rotteveel Over a year ago

Although this code might answer the question, I recommend that you also provide an explanation what your code does and how it solves the problem of the question. Answers with an explanation are usually more helpful and of better quality, and are more likely to attract upvotes.

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