请问如何限制HTML中textarea输入字符的数量？

textarea没有类似方法。

<textarea name="content" cols="60" rows="6" onKeyUp="if(this.value.length >300) this.value=this.value.substr(0,300)">

意思就是，大于300个字符，自动截取前300个，后面忽略

上面那位朋友说的

<textarea name="A" cols="45" rows="2" onKeyDown="if (this.value.length>=20){event.returnValue=false}">aaaa</textarea>

也可以

var CSSrules = {

'textarea' : function(element){

element.onkeydown = function(event){

return doKeyPress(element,event)

}

,

element.onpaste = function(){

return doPaste(element)

}

,

element.onkeyup = function(){

return doKeyUp(element)

}

,

element.onblur = function(){

return doKeyUp(element)

}

}

}Behaviour.register(CSSrules)var detect = navigator.userAgent.toLowerCase()// Keep user from entering more than maxLength characters

function doKeyPress(obj,evt){//键入时

maxLength = obj.getAttribute("maxlength")

var e = window.event ? event.keyCode : evt.which

if ( (e == 32) || (e == 13) || (e >47)) { //IE

if(maxLength &&(obj.value.length >maxLength-1)) {

if (window.event) {

window.event.returnValue = null

} else {

evt.cancelDefault

return false

}

}

}

}

function doKeyUp(obj){//按键时

maxLength = obj.getAttribute("maxlength")

if(maxLength &&obj.value.length >maxLength){

obj.value = obj.value.substr(0,maxLength)

}

sr = obj.getAttribute("showremain")

if (sr) {

document.getElementById(sr).innerHTML = maxLength-obj.value.length//sr是剩余可添加字符数

}

}// Cancel default behavior and create a new paste routine

function doPaste(obj){ //复制时

maxLength = obj.getAttribute("maxlength")

if(maxLength){

if ((window.event) &&(detect.indexOf("safari") + 1 == 0)) { //IE

var oTR = obj.document.selection.createRange()

var iInsertLength = maxLength - obj.value.length + oTR.text.length

try {

var sData = window.clipboardData.getData("Text").substr(0,iInsertLength)//截断多余的字符

oTR.text = sData

}

catch (err) {

}

if (window.event) { //IE

window.event.returnValue = null

} else {

//not IE

obj.value = obj.value.substr(0,maxLength)

return false

}

}

}

}

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