在input输入框光标位置插入内容

let input = document.getElementById('input')

let textToInsert = '我是插入的内容';

let startPosition = input.selectionStart;

let endPosition = input.selectionEnd;

input.value = input.value.substring(0, startPosition) + textToInsert + input.value.substring(endPosition, input.value.length);

input.setSelectionRange(startPosition + textToInsert.length, startPosition + textToInsert.length);

input.focus()