textarea自适应高度，显示滚动条
调用
autosize(document.querySelectorAll('textarea'));
/*!
Autosize 2.0.0
license: MIT
textarea根据内容自动延伸，显示滚动条
*/
(function (root, factory) {
'use strict';
if (typeof define === 'function' && define.amd) {
// AMD. Register as an anonymous module.
define([], factory);
} else if (typeof exports === 'object') {
// Node. Does not work with strict CommonJS, but
// only CommonJS-like environments that support module.exports,
// like Node.
module.exports = factory();
} else {
// Browser globals (root is window)
root.autosize = factory();
}
}(this, function () {
function main(ta) {
if (!ta || !ta.nodeName || ta.nodeName !== 'TEXTAREA' || ta.hasAttribute('data-autosize-on')) { return; }
var maxHeight;
var heightOffset;
function init() {
var style = window.getComputedStyle(ta, null);
if (style.resize === 'vertical') {
ta.style.resize = 'none';
} else if (style.resize === 'both') {
ta.style.resize = 'horizontal';
}
// horizontal overflow is hidden, so break-word is necessary for handling words longer than the textarea width
ta.style.wordWrap = 'break-word';
// Chrome/Safari-specific fix:
// When the textarea y-overflow is hidden, Chrome/Safari doesn't reflow the text to account for the space
// made available by removing the scrollbar. This workaround will cause the text to reflow.
var width = ta.style.width;
ta.style.width = '0px';
// Force reflow:
/* jshint ignore:start */
ta.offsetWidth;
/* jshint ignore:end */
ta.style.width = width;
maxHeight = style.maxHeight !== 'none' ? parseFloat(style.maxHeight) : false;
if (style.boxSizing === 'content-box') {
heightOffset = -(parseFloat(style.paddingTop)+parseFloat(style.paddingBottom));
} else {
heightOffset = parseFloat(style.borderTopWidth)+parseFloat(style.borderBottomWidth);
}
adjust();
}
function adjust() {
var startHeight = ta.style.height;
var htmlTop = document.documentElement.scrollTop;
var bodyTop = document.body.scrollTop;
ta.style.height = '16px';
var endHeight = ta.scrollHeight+heightOffset;
if (maxHeight !== false && maxHeight < endHeight) {
endHeight = maxHeight;
if (ta.style.overflowY !== 'scroll') {
ta.style.overflowY = 'scroll';
}
} else if (ta.style.overflowY !== 'hidden') {
ta.style.overflowY = 'hidden';
}
ta.style.height = endHeight+'px';
// prevents scroll-position jumping
document.documentElement.scrollTop = htmlTop;
document.body.scrollTop = bodyTop;
if (startHeight !== ta.style.height) {
var evt = document.createEvent('Event');
evt.initEvent('autosize.resized', true, false);
ta.dispatchEvent(evt);
}
}
// IE9 does not fire onpropertychange or oninput for deletions,
// so binding to onkeyup to catch most of those events.
// There is no way that I know of to detect something like 'cut' in IE9.
if ('onpropertychange' in ta && 'oninput' in ta) {
ta.addEventListener('keyup', adjust);
}
window.addEventListener('resize', adjust);
ta.addEventListener('focus', adjust);
ta.addEventListener('input', adjust);
ta.addEventListener('autosize.update', adjust);
ta.addEventListener('autosize.destroy', function(style){
window.removeEventListener('resize', adjust);
ta.removeEventListener('focus', adjust);
ta.removeEventListener('input', adjust);
ta.removeEventListener('keyup', adjust);
ta.removeEventListener('autosize.destroy');
Object.keys(style).forEach(function(key){
ta.style[key] = style[key];
});
ta.removeAttribute('data-autosize-on');
}.bind(ta, {
height: ta.style.height,
overflow: ta.style.overflow,
overflowY: ta.style.overflowY,
wordWrap: ta.style.wordWrap,
resize: ta.style.resize
}));
ta.setAttribute('data-autosize-on', true);
ta.style.overflow = 'hidden';
ta.style.overflowY = 'hidden';
init();
}
// Do nothing in IE8 or lower
if (typeof window.getComputedStyle !== 'function') {
return function(elements) {
return elements;
};
} else {
return function(elements) {
if (elements && elements.length) {
Array.prototype.forEach.call(elements, main);
} else if (elements && elements.nodeName) {
main(elements);
}
return elements;
};
}
}));
