Sorting Table with javascript-CodePudding

I have a simple table in HTML like this :

    <table id="myTable">
<thead>
  <tr>
    <th class="pointer" onClick="sortTable()">Number</th>
    <th>Example3</th>
    <th>Example2</th>
    <th>Example1</th>
  </tr>
</thead>
<tbody>
  <tr>
    <td>101</td>
    <td>TOM</td>
    <td>Not Working</td>
    <td>AUTOMAT-01</td>
  </tr>
  <tr>
    <td>102</td>
    <td>TOM</td>
    <td>Not Working</td>
    <td>AUTOMAT-02</td>
  </tr>
</tbody>
  
</table>

and function for sorting this table in javascript but it's not working. I would like to sort the table descending by Column number. How to fix this? I would like also to add an arrow next to the column name to call function by clicking the arrow

function sortTable() {
  var table, rows, switching, i, x, y, shouldSwitch;
  table = document.getElementById("myTable");
  switching = true;
  /*Make a loop that will continue until
  no switching has been done:*/
  while (switching) {
    //start by saying: no switching is done:
    switching = false;
    rows = table.rows;
    /*Loop through all table rows (except the
    first, which contains table headers):*/
    for (i = 1; i < (rows.length - 1); i  ) {
      //start by saying there should be no switching:
      shouldSwitch = false;
      /*Get the two elements you want to compare,
      one from current row and one from the next:*/
      x = rows[i].getElementsByTagName("TD")[0];
      y = rows[i   3].getElementsByTagName("TD")[0];
      //check if the two rows should switch place:
      if (Number(x.innerHTML) > Number(y.innerHTML)) {
        //if so, mark as a switch and break the loop:
        shouldSwitch = true;
        break;
      }
    }
    if (shouldSwitch) {
      /*If a switch has been marked, make the switch
      and mark that a switch has been done:*/
      rows[i].parentNode.insertBefore(rows[i   3], rows[i]);
      switching = true;
    }
  }
}

CodePudding user response：

Why switch with rows[i 3] and not rows[i 1]? Why break the loop, and don't continue until the end?

function sortTable() {
  var table, rows, switching, x, y;
  table = document.getElementById("myTable");
  /*Make a loop that will continue until
  no switching has been done:*/
  do {
    //start by saying: no switching is done:
    switching = false;
    rows = table.rows;
    /*Loop through all table rows (except the
    first, which contains table headers):*/
    for (var i = 1; i < (rows.length - 1); i  ) {
      //start by saying there should be no switching:
      /*Get the two elements you want to compare,
      one from current row and one from the next:*/
      x = rows[i].getElementsByTagName("TD")[0];
      y = rows[i   1].getElementsByTagName("TD")[0];
      //check if the two rows should switch place:
      if (Number(x.innerHTML) > Number(y.innerHTML)) {
        //if so, mark as a switch
        switching = true;
        rows[i].parentNode.insertBefore(rows[i   1], rows[i]);
        rows = table.rows;
      }
    }
    // run until no switches
  } while (switching)
}

<table id="myTable">
<thead>
  <tr>
    <th class="pointer" onClick="sortTable()">Number</th>
    <th>Example3</th>
    <th>Example2</th>
    <th>Example1</th>
  </tr>
</thead>
<tbody>
  <tr>
    <td>101</td>
    <td>TOM</td>
    <td>Not Working</td>
    <td>AUTOMAT-01</td>
  </tr>
  <tr>
    <td>102</td>
    <td>TOM</td>
    <td>Not Working</td>
    <td>AUTOMAT-02</td>
  </tr>
  <tr>
    <td>100</td>
    <td>TOM</td>
    <td>Not Working</td>
    <td>AUTOMAT-00</td>
  </tr>
</tbody>
  
</table>

CodePudding user response：

If you had read little bit more the page you were on (https://www.w3schools.com/howto/howto_js_sort_table.asp) , you could find the answer of this question.

function sortTable(n) {
  var table, rows, switching, i, x, y, shouldSwitch, dir, switchcount = 0;
  table = document.getElementById("myTable");
  switching = true;
  // Set the sorting direction to ascending:
  dir = "asc";
  /* Make a loop that will continue until
  no switching has been done: */
  while (switching) {
    // Start by saying: no switching is done:
    switching = false;
    rows = table.rows;
    /* Loop through all table rows (except the
    first, which contains table headers): */
    for (i = 1; i < (rows.length - 1); i  ) {
      // Start by saying there should be no switching:
      shouldSwitch = false;
      /* Get the two elements you want to compare,
      one from current row and one from the next: */
      x = rows[i].getElementsByTagName("TD")[n];
      y = rows[i   1].getElementsByTagName("TD")[n];
      /* Check if the two rows should switch place,
      based on the direction, asc or desc: */
      if (dir == "asc") {
        if (x.innerHTML.toLowerCase() > y.innerHTML.toLowerCase()) {
          // If so, mark as a switch and break the loop:
          shouldSwitch = true;
          break;
        }
      } else if (dir == "desc") {
        if (x.innerHTML.toLowerCase() < y.innerHTML.toLowerCase()) {
          // If so, mark as a switch and break the loop:
          shouldSwitch = true;
          break;
        }
      }
    }
    if (shouldSwitch) {
      /* If a switch has been marked, make the switch
      and mark that a switch has been done: */
      rows[i].parentNode.insertBefore(rows[i   1], rows[i]);
      switching = true;
      // Each time a switch is done, increase this count by 1:
      switchcount   ;
    } else {
      /* If no switching has been done AND the direction is "asc",
      set the direction to "desc" and run the while loop again. */
      if (switchcount == 0 && dir == "asc") {
        dir = "desc";
        switching = true;
      }
    }
  }
}

    <table id="myTable">
<thead>
  <tr>
    <th class="pointer" onClick="sortTable(0)">Number</th>
    <th>Example3</th>
    <th>Example2</th>
    <th>Example1</th>
  </tr>
</thead>
<tbody>
  <tr>
    <td>101</td>
    <td>TOM</td>
    <td>Not Working</td>
    <td>AUTOMAT-01</td>
  </tr>
  <tr>
    <td>102</td>
    <td>TOM</td>
    <td>Not Working</td>
    <td>AUTOMAT-02</td>
  </tr>
</tbody>
  
</table>

Here associated fiddle : https://jsfiddle.net/Louf0sc7/