我不知道如何很好地解释它，但我正在尝试构建一个随文本自动扩展的文本区域，但是我找到的所有示例，文本区域向下增长，我希望文本区域向上增长。
例子：
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();
}textarea {
border: 0 none white;
overflow: hidden;
padding: 0;
outline: none;
background-color: #D0D0D0;
resize: none;
}<body onload="init();">
<textarea rows="1" style="height:1em;" id="text"></textarea>
</body>http://jsfiddle.net/0a9u7h2g/2/
如何更改此代码以实现此目的？
我假设你的意思是它应该向上增长，而不是向下增长。通过将textarea放在其包含元素的底部，它将被迫向上生长。
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();
}textarea {
border: 0 none white;
overflow: hidden;
padding: 0;
outline: none;
background-color: #D0D0D0;
resize: none;
width: 100px;
}
body {
height: 90vh;
display: flex;
flex-direction: column;
justify-content: flex-end;
align-items: center;
}<body onload="init();">
<textarea rows="1" style="height:1em;" id="text"></textarea>
</body>