如何在自动调整textarea中键入时停止窗口跳转

eir*_*vey 3 javascript textarea autoresize

我正在使用这个问题的接受答案来构建一个textarea,它随着文本溢出而垂直扩展:

<!DOCTYPE html>
<html>
<head>
<title>autoresizing textarea</title>
<style type="text/css">
textarea {
 border: 0 none white;
 overflow: hidden;
 padding: 0;
 outline: none;
 background-color: #D0D0D0;
 resize: none;
}
</style>
<script type="text/javascript">
var observe;
if (window.attachEvent) {
 observe = function (element, event, handler) {
  element.attachEvent('on'+event, handler);
 };
}
else {
 observe = function (element, event, handler) {
  element.addEventListener(event, handler, false);
 };
}
function init () {
 var text = document.getElementById('text');
 function resize () {
  text.style.height = 'auto';
  text.style.height = text.scrollHeight+'px';
 }
 /* 0-timeout to get the already changed text */
 function delayedResize () {
  window.setTimeout(resize, 0);
 }
 observe(text, 'change',  resize);
 observe(text, 'cut',     delayedResize);
 observe(text, 'paste',   delayedResize);
 observe(text, 'drop',    delayedResize);
 observe(text, 'keydown', delayedResize);

 text.focus();
 text.select();
 resize();
}
</script>
</head>
<body onload="init();">
<textarea rows="1" style="height:1em;" id="text"></textarea>
</body>
</html>
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它很有效,直到textarea的大小比浏览器窗口长.此时,每按一次键,窗口顶部就会跳到文本区域的顶部.你能帮我理解为什么以及如何解决它吗?

理想的解决方法是保持页面不移动.但是如果将页面底部绑在textarea的底部更容易,那也可以.

我在Firefox 21.0和Chrome 28.0中遇到此问题:http://jsfiddle.net/CbqFv/

los*_*nir 8

保存scrollLeft,scrollTop值,然后在调整textarea大小后恢复它们:

function resize () {
   var scrollLeft = window.pageXOffset ||
   (document.documentElement || document.body.parentNode || document.body).scrollLeft;

   var scrollTop  = window.pageYOffset ||
   (document.documentElement || document.body.parentNode || document.body).scrollTop;

   text.style.height = "auto";
   text.style.height = text.scrollHeight + 'px';

   window.scrollTo(scrollLeft, scrollTop);
}
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JSFiddle:http://jsfiddle.net/losnir/nnkeH/1