1.使用拆分
1.使用分块器-我在Split array into chunks找到了一个
1.可以使用模板文本生成字符串
此选项仅在最后一个选项上添加files属性，并且仅当其大于chunksize时添加

const chunker = (list, size) => list.value.trim().split(',').reduce((acc, cur, i) => { const ch = Math.floor(i / size); acc[ch] = [].concat((acc[ch] || []), cur); return acc }, []);

const myList = document.getElementById('mylist');
const myNewList = document.getElementById('mynewlist');
const chunkSize = 3;
document.getElementById('generate').addEventListener('click', () => {
  let chunks = chunker(myList, chunkSize),
    lastChunk = [...chunks[chunks.length - 1]], 
    partial = lastChunk.length < chunkSize,
    max = chunks.length-2; // max is only used if partial
  if (partial) {
    chunks = chunks.slice(0, -1); // chop the last off
    chunks[chunks.length - 1] = chunks[chunks.length - 1].concat(lastChunk); // concat to new last chunk
  }
  myNewList.value = chunks.map((chunk, i) => `<!--startline-->[new text="table"${partial && i===max ? ' files="2"' : '' } ids="${chunk.join(',')}"]`).join('\n')

});

#mynewlist {
  width: 700px;
  height: 300px;
}

<textarea id="mylist">30318,30319,30320,30321,30322,30323,30324,30325,30326,30327,30328,30329,30330,30331,30332,30333,30334,30335,30336,30337,30338,30339,30340,30341,30342,30343,30344,30345,30346,30347,30348,30349,30350,30351,30352,30353,30354,30355,30356,30357,30358,30359,30360,30361,30362,30363,30364,30365,123,999</textarea>
<br><br>
<button id="generate">Generate new list</button>
<br><br>
<textarea id="mynewlist"></textarea>