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Javascript add new line to table and replace IDs

I'm a hobby coder and struggle with following issue: I got a table element with a few rows, each row 3 cells. Via a button at the bottom I would like to add rows. The table looks like this:

<table id="mytable">
  <tr id="line[0]"><td id="cellA[0]"</td><td id="cellB[0]"</td><td id="cellC[0]"</td></tr>
  <tr id="line[1]"><td id="cellA[1]"</td><td id="cellB[1]"</td><td id="cellC[1]"</td></tr>
  <tr id="line[2]"><td id="cellA[2]"</td><td id="cellB[2]"</td><td id="cellC[2]"</td></tr>
</table>

I loop through with elementbyID "line" to find that the last line is [2]. And then add a new line like this:

var table = document.getElementById("mytable");
var row = table.insertRow(oldID + 1);
row.setAttribute("id","line["+ oldID + 1 + "]");

This works great.

Next I get the content of the last line via var lastLine = document.getElementById(oldID).innerHTML. Now since the td IDs are cellA[2], cellB[2] and cellC[2]. I would like to replace those with [3].

I tried following:

var oldVar = "[" + oldID + "]";
var newVar = "[" + oldID + 1 + "]";
var regex = new RegExp(oldVar, "g");
var neueLine = lastLine.replace(regex, newVar);

but this results in ids like this "cellA[3][3]", "cellB[3][3]" and "cellC[3][3]".

I feel like my limited knowledge is missing out on the supposed way to do this.

Thanks a lot for your help!

3 months ago ·

Juan Pablo Isaza

2 answers

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Answer 1 · 2022-07-07T01:48:14.457Z

You can use replaceAll

lastLine = lastLine.replaceAll("[" + oldID + "]","[" + (oldID+1) + "]")

Answer 2 · 2022-07-07T01:48:14.466Z

This will work - it can possibly be coded in less instructions but is very readable. Also I fixed the invalid HTML

window.addEventListener("load", function() {
  const table = document.querySelector("#mytable tbody");
  document.getElementById("add").addEventListener("click", function() {
    const lastRow = table.querySelector("tr:last-child")
    let id = +lastRow.id.replace(/\D+/g, ""); // grab and convert to number
    let newId = id+1;
    const newLine = lastRow.cloneNode(true);
    newLine.id = newLine.id.replace(id,newId);
    newLine.querySelectorAll("td").forEach(cell => cell.id = cell.id.replace(id,newId))
    table.appendChild(newLine)
  })
})

<input type="button" id="add" value="Add" />
<table id="mytable">
  <tbody>
    <tr id="line[0]">
      <td id="cellA[0]">A</td>
      <td id="cellB[0]">B </td>
      <td id="cellC[0]">C</td>
    </tr>
    <tr id="line[1]">
      <td id="cellA[1]">A </td>
      <td id="cellB[1]">B</td>
      <td id="cellC[1]">C </td>
    </tr>
    <tr id="line[2]">
      <td id="cellA[2]">A</td>
      <td id="cellB[2]">B</td>
      <td id="cellC[2]">C</td>
    </tr>
  </tbody>
</table>