[HTML][JS] 為 textarea 增加 maxlength 屬性

[HTML][JS] 為 textarea 增加 maxlength 屬性

o 如果只是單純地想限制 textarea 中的字數,不想寫太多的話,可用:

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

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

o 在 textarea 的 onkeyup 中檢查字數之方法:

.....
<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 設定好自動去檢查所有的 textarea 之方法:

.....
<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();">
.....
這篇文章的關鍵字(Keyword): textarea maxlength, maxlenght textarea html, maxlenght int textarea
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