当前位置： 移动技术网 > IT编程>开发语言>JavaScript > TextArea 控件的最大长度问题(js json)

TextArea 控件的最大长度问题(js json)

2019年07月19日  | 移动技术网IT编程  | 我要评论
如果只是单纯地想限制 textarea 中的字数，不想写太多的话，可用：

<textarea onkeyup="this.value = this.value.slice(0, 80)"></textarea>

或

<textarea onkeyup="this.value = this.value.substring(0, 80)"></textarea>

在 textarea 的 onkeyup 中检查字数之方法：
复制代码 代码如下:

<script language="javascript" type="text/javascript">
function djcheckmaxlength(oinobj)
{
var imaxlen = parseint(oinobj.getattribute('maxlength'));
var icurlen = oinobj.value.length;

if ( oinobj.getattribute && icurlen > imaxlen )
{
oinobj.value = oinobj.value.substring(0, imaxlen);
}
} //@ end of djcheckmaxlength()
</script>
<textarea maxlength="80" onkeyup="return djcheckmaxlength(this);"></textarea>

o 设定好自动去检查所有的 textarea 之方法：
复制代码 代码如下:

<head>
<script language="javascript" type="text/javascript">
function djtextarea_addmaxlengthattr()
{
var ax = document.getelementsbytagname('textarea');

for ( var ii = 0; ax.length > ii; ii++ )
{
if ( ax[ii].getattribute('maxlength') )
{
ax[ii].onkeyup = ax[ii].onchange = djtextarea_checkmaxlength;
}
}
} //@ end of djtextarea_addmaxlengthattr()

function djtextarea_checkmaxlength()
{
var imaxlen = parseint(this.getattribute('maxlength'));
var icurlen = this.value.length;

if ( this.getattribute && icurlen > imaxlen )
{
this.value = this.value.substring(0, imaxlen);
}
} //@ end of djtextarea_checkmaxlength()
</script>
</head>

<body onload="djtextarea_addmaxlengthattr();">

复制代码 代码如下:

var inputs = {

onintegeronly: function() {
var k = system.isie ? event.keycode : event.which;

if(event.ctrlkey || event.ctrlalt || event.shiftkey) {
inputs.disableinput(event);
return;
}

if ( ( k < 48 || k > 57 )
&& 8 != k
&& 9 != k
&& 46 != k
&& 37 != k
&& 39 != k
&& 16 != k
&& 36 != k
&& 35 != k
&& 17 != k
&& 13 != k
&& ( k < 96 || k > 105 )
) {
inputs.disableinput(event);
}

return k;
},

ondecimalonly: function() {
var k = system.isie ? event.keycode : event.which;

if(event.ctrlkey || event.ctrlalt || event.shiftkey) {
inputs.disableinput(event);
return;
}

if( ( k < 48 || k > 57 )
&& 8 != k
&& 9 != k
&& 46 != k
&& 37 != k
&& 39 != k
&& 16 != k
&& 36 != k
&& 35 != k
&& 17 != k
&& 13 != k
&& 190 != k
&& 110 != k
&& ( k < 96 || k > 105 )
) {
inputs.disableinput(event);
}

return k;
},

onasciionly: function() {
var k = system.isie ? event.keycode : event.which;

if ( ( k < 97 || k > 122 )
&& ( k < 65 || k > 90 )
&& ( k < 48 || k > 57 )
&& 8 != k
&& 9 != k
&& 46 != k
&& 37 != k
&& 39 != k
&& 16 != k
&& 36 != k
&& 35 != k
&& 17 != k
&& 13 != k
&& 189 != k
&& 187 != k
) {
inputs.disableinput(event);
}

return k;
},

disableinput: function(event) {
if(system.isie)
event.returnvalue = false;
else
event.preventdefault();
},

addonpos: function(obj, charvalue) {
//obj代表要插入字符的输入框

//value代表要插入的字符

obj.focus();
var r = document.selection.createrange();
var ctr = obj.createtextrange();
var i;
var s = obj.value;

//注释掉的这种方法只能用在单行的输入框input内

//对多行输入框textarea无效
//r.setendpoint("starttostart", ctr);
//i = r.text.length;
//取到光标位置----start----
var ivalue = "&^asdjfls2ffff325%$^&";
r.text = ivalue;
i = obj.value.indexof(ivalue);
r.movestart("character", -ivalue.length);
r.text = "";
//取到光标位置----end----
//插入字符
obj.value = s.substr(0,i) + charvalue + s.substr(i,s.length);
ctr.collapse(true);
ctr.movestart("character", i + charvalue.length);
ctr.select();
},

maxlength: function() {
var _this = event.srcelement;
var imaxlen = parseint(_this.getattribute('maxlength'));

switch(event.type) {
case 'beforepaste': {
event.returnvalue = false;
} break;

case 'paste': {
var itxtlen = _this.value.lenutf8();
var txtcbd = window.clipboarddata.getdata("text");
var icbdlen = txtcbd.lenutf8();
if((imaxlen - itxtlen) <= icbdlen) {
var isurpluslen = imaxlen - itxtlen;
var substr = txtcbd.substr(0, isurpluslen);
var insertstr = '';
for(var i = 0; i < substr.length; i++) {
var chr = substr.substr(i, 1);
if(isurpluslen >= chr.lenutf8()) {
insertstr += chr;
isurpluslen -= chr.lenutf8();
}
}

inputs.addonpos(_this, insertstr);
//_this.style.backgroundcolor = 'red';
//system.settimeout(inputs.colortips, 500, _this);
event.returnvalue = false;
event.srcelement.style.imemode = 'disabled';
} else {
event.returnvalue = true;
event.srcelement.style.imemode = 'auto';
}
} break;

case 'keypress': {
var itxtlen = _this.value.lenutf8();
if(imaxlen <= itxtlen) {
while(_this.value.lenutf8() > imaxlen) {
_this.value = _this.value.substr(0, _this.value.length - 1);
}
inputs.disableinput(event);
if('disabled' != event.srcelement.style.imemode) {
event.srcelement.style.imemode = 'disabled';
}
}
else {
if('auto' != event.srcelement.style.imemode) {
event.srcelement.style.imemode = 'auto';
}
}
} break;

case 'keyup': {
var k = system.isie ? event.keycode : event.which;

if (8 != k
&& 9 != k
&& 46 != k
&& 37 != k
&& 39 != k
&& 16 != k
&& 36 != k
&& 35 != k
&& 17 != k
&& 13 != k
&& 189 != k
&& 187 != k
) {
if(_this.getattribute) {
_this.fireevent('onkeypress');
}
}
} break;

case 'keydown': {
var k = system.isie ? event.keycode : event.which;

if (8 != k
&& 9 != k
&& 46 != k
&& 37 != k
&& 39 != k
&& 16 != k
&& 36 != k
&& 35 != k
&& 17 != k
&& 13 != k
&& 189 != k
&& 187 != k
) {
var itxtlen = _this.value.lenutf8();
if(imaxlen <= itxtlen) {
inputs.disableinput(event);
}
}
} break;
}
},

textareamaxlength: function() {

var ax = document.getelementsbytagname('textarea');
for(var i = 0; i < ax.length; i++) {
if(ax[i].getattribute('maxlength')) {
ax[i].detachevent('onbeforepaste', inputs.maxlength);
ax[i].detachevent('onpaste', inputs.maxlength);
ax[i].detachevent('onkeypress', inputs.maxlength);
ax[i].detachevent('onkeyup', inputs.maxlength);
ax[i].detachevent('onkeydown', inputs.maxlength);

ax[i].attachevent('onbeforepaste', inputs.maxlength);
ax[i].attachevent('onpaste', inputs.maxlength);
ax[i].attachevent('onkeypress', inputs.maxlength);
ax[i].attachevent('onkeyup', inputs.maxlength);
ax[i].attachevent('onkeydown', inputs.maxlength);
/*
var res = 'zh-cn' == window.navigator.systemlanguage
? '最大长度：'
: 'maximum length for: ';

if('' == ax[i].title) ax[i].title = res + ax[i].getattribute('maxlength');
*/
}
}
},

textboxmaxlength: function() {
var ax = document.getelementsbytagname('input');
for(var i = 0; i < ax.length; i++) {
var maxlen = ax[i].getattribute('maxlength');
if('text' == ax[i].type
&& null != maxlen
&& '' != maxlen
&& undefined != maxlen
&& 2147483647 > parseint(maxlen)
&& '' == ax[i].title) {

ax[i].detachevent('onbeforepaste', inputs.maxlength);
ax[i].detachevent('onpaste', inputs.maxlength);
ax[i].detachevent('onkeypress', inputs.maxlength);
ax[i].detachevent('onkeyup', inputs.maxlength);

ax[i].attachevent('onbeforepaste', inputs.maxlength);
ax[i].attachevent('onpaste', inputs.maxlength);
ax[i].attachevent('onkeypress', inputs.maxlength);
ax[i].attachevent('onkeyup', inputs.maxlength);
/*
var res = 'zh-cn' == window.navigator.systemlanguage
? '最大长度：'
: 'maximum length for: ';

ax[i].title = res + ax[i].getattribute('maxlength');
*/
}
}
}
}

tools.inputs = inputs;

window.attachevent('onload', tools.inputs.textareamaxlength);
window.attachevent('onload', tools.inputs.textboxmaxlength);

您可能感兴趣的文章:

如对本文有疑问， 点击进行留言回复！！

相关文章:

验证码：
最近更新的文章
大家感兴趣的文章
移动技术网