<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>Document</title>
</head>
<body>
<div id='inputDiv' style=" 300px;height:300px;margin:0 auto;border:1px solid #30f;" contenteditable="true">
</div>
<button id='btn'>点击获取</button>
</body>
<script>
var oDiv = document.getElementById('inputDiv')
document.getElementById('btn').onclick = function(){
console.log(oDiv.innerHTML)
}
</script>
</html>
给div标签一个属性contenteditable="true"，当前div就可以像textarea输入信息。获取的方式是直接获取div内容。代码运行可以试一下结果