获取可编辑div光标所在行

//获取光标所在行

const getCaretLine = (element) => {
let caretOffset = 0;
let sel = window.getSelection();
if(sel.rangeCount > 0) {
let range = sel.getRangeAt(0);
let preCaretRange = range.cloneRange();
preCaretRange.selectNodeContents(element);
preCaretRange.setEnd(range.endContainer,range.endOffset);
caretOffset = preCaretRange.toString().length;
}
let ar = element.textContent.substring(0, caretOffset).split('n');
return ar[ar.length - 1];
};