<table id="table">
  <thead>
    <tr>
      <td>Column 1</td>
      <td>Column 2</td>
      <td>Column 3</td>
      <td>Column 4</td>
      <td>Column 5</td>
    </tr>
  </thead>
  <tbody>
    <tr>
      <td>Value 1</td>
      <td>Value 2</td>
      <td>Value 3</td>
      <td>Value 4</td>
      <td>Value 5</td>
    </tr>
    <tr>
      <td>Value 1</td>
      <td>Value 2</td>
      <td>Value 3</td>
      <td>Value 4</td>
      <td>Value 5</td>
    </tr>
    <tr>
      <td>Value 1</td>
      <td>Value 2</td>
      <td>Value 3</td>
      <td>Value 4</td>
      <td>Value 5</td>
    </tr>
    <tr>
      <td>Value 1</td>
      <td>Value 2</td>
      <td>Value 3</td>
      <td>Value 4</td>
      <td>Value 5</td>
    </tr>
    <tr>
      <td>Value 1</td>
      <td>Value 2</td>
      <td>Value 3</td>
      <td>Value 4</td>
      <td>Value 5</td>
    </tr>
    <tr>
      <td>Value 1</td>
      <td>Value 2</td>
      <td>Value 3</td>
      <td>Value 4</td>
      <td>Value 5</td>
    </tr>
    <tr>
      <td>Value 1</td>
      <td>Value 2</td>
      <td>Value 3</td>
      <td>Value 4</td>
      <td>Value 5</td>
    </tr>
    <tr>
      <td>Value 1</td>
      <td>Value 2</td>
      <td>Value 3</td>
      <td>Value 4</td>
      <td>Value 5</td>
    </tr>
  </tbody>
</table>
let indexColumn = 5,
    dataColumns = [...document.querySelectorAll('#table td:nth-child('+indexColumn+')')].map(item => item.innerHTML);

console.log(dataColumns) // ["Column 5", "Value 5", "Value 5", "Value 5", "Value 5", "Value 5", "Value 5", "Value 5", "Value 5"]

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