Home >Web Front-end >JS Tutorial >The maximum length problem of TextArea control (js json)_form special effects
The maximum length problem of TextArea control (js json)_form special effects

WBOYOriginal: 2016-05-16 18:39:151125browse
If you simply want to limit the number of words in the textarea and don't want to write too much, you can use:

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

How to check the word count in onkeyup of textarea:
Copy the code The code is as follows:
 
 
< ;/textarea> <br>
</div> <br><strong>o Set up the method to automatically check all textareas: </strong> <br><div class="codetitle">
<span><a style="CURSOR: pointer" data="58200" class="copybut" id="copybut58200" onclick="doCopy('code58200')"><u>Copy code</u></a></span> The code is as follows: </div>
<div class="codebody" id="code58200"> <br><head> <br><script language="javascript" type="text/javascript"> <br>function DjTextArea_AddMaxlengthAttr( ) <br>{ <br>var aX = document.getElementsByTagName('textarea'); <br><br>for ( var iI = 0; aX.length > iI; iI ) <br>{ <br>if ( aX[iI].getAttribute('maxlength') ) <br>{ <br>aX[iI].onkeyup = aX[iI].onchange = DjTextArea_CheckMaxlength; <br>} <br>} <br>} // @ END OF DjTextArea_AddMaxlengthAttr() <br><br>function DjTextArea_CheckMaxlength() <br>{ <br>var iMaxLen = parseInt(this.getAttribute('maxlength')); <br>var iCurLen = this.value.length; <br><br>if ( this.getAttribute && iCurLen > iMaxLen ) <br>{ <br>this.value = this.value.substring(0, iMaxLen); <br>} <br>} //@ END OF DjTextArea_CheckMaxlength() <br></script> <br></head> <br><br><body onload="DjTextArea_AddMaxlengthAttr();"> <br>
</div>
<br><div class="codetitle">
<span><a style="CURSOR: pointer" data="36174" class="copybut" id="copybut36174" onclick="doCopy('code36174')"><u>Copy code</u></a></span> The code is as follows:</div>
<div class="codebody" id="code36174">
<br>var Inputs = { <br><br>OnIntegerOnly: function() { <br>var k = System.isIE ? event.keyCode : event.which; <br><br>if(event.ctrlKey || event.ctrlAlt || event.shiftKey) { <br>Inputs.DisableInput(event); <br>return; <br>} <br><br>if ( ( k < 48 || k > 57 ) <br>&& 8 != k <br>&& 9 != k <br>&& 46 != k <br>&& 37 != k <br>&& 39 != k <br>&& 16 != k <br>&& 36 != k <br>&& 35 != k <br>&& 17 != k <br>&& 13 != k <br>&& ( k < 96 || k > 105 ) <br>) { <br>Inputs.DisableInput(event); <br>} <br><br>return k; <br>}, <br><br>OnDecimalOnly: function() { <br>var k = System.isIE ? event.keyCode : event.which; <br><br>if(event.ctrlKey || event.ctrlAlt || event.shiftKey) { <br>Inputs.DisableInput(event); <br>return; <br>} <br><br>if( ( k < 48 || k > 57 ) <br>&& 8 != k <br>&& 9 != k <br>&& 46 != k <br>&& 37 != k <br>&& 39 != k <br>&& 16 != k <br>&& 36 != k <br>&& 35 != k <br>&& 17 != k <br>&& 13 != k <br>&& 190 != k <br>&& 110 != k <br>&& ( k < 96 || k > 105 ) <br>) { <br>Inputs.DisableInput(event); <br>} <br><br>return k; <br>}, <br><br>OnAsciiOnly: function() { <br>var k = System.isIE ? event.keyCode : event.which; <br><br>if ( ( k < 97 || k > 122 ) <br>&& ( k < 65 || k > 90 ) <br>&& ( k < 48 || k > 57 ) <br>&& 8 != k <br>&& 9 != k <br>&& 46 != k <br>&& 37 != k <br>&& 39 != k <br>&& 16 != k <br>&& 36 != k <br>&& 35 != k <br>&& 17 != k <br>&& 13 != k <br>&& 189 != k <br>&& 187 != k <br>) { <br>Inputs.DisableInput(event); <br>} <br><br>return k; <br>}, <br><br>DisableInput: function(event) { <br>if(System.isIE) <br>event.returnValue = false; <br>else <br>event.preventDefault(); <br>}, <br><br>AddOnPos: function(obj, charvalue) { <br>//obj代表要插入字符的输入框 <br><br>//value代表要插入的字符 <br><br>obj.focus(); <br>var r = document.selection.createRange(); <br>var ctr = obj.createTextRange(); <br>var i; <br>var s = obj.value; <br><br>//注释掉的这种方法只能用在单行的输入框input内 <br><br>//对多行输入框textarea无效 <br>//r.setEndPoint("StartToStart", ctr); <br>//i = r.text.length; <br>//取到光标位置----Start---- <br>var ivalue = "&^asdjfls2FFFF325%$^&"; <br>r.text = ivalue; <br>i = obj.value.indexOf(ivalue); <br>r.moveStart("character", -ivalue.length); <br>r.text = ""; <br>//取到光标位置----End---- <br>//插入字符 <br>obj.value = s.substr(0,i)   charvalue   s.substr(i,s.length); <br>ctr.collapse(true); <br>ctr.moveStart("character", i   charvalue.length); <br>ctr.select(); <br>}, <br><br>MaxLength: function() { <br>var _this = event.srcElement; <br>var iMaxLen = parseInt(_this.getAttribute('maxlength')); <br><br>switch(event.type) { <br>case 'beforepaste': { <br>event.returnValue = false; <br>} break; <br><br>case 'paste': { <br>var iTxtLen = _this.value.lenUTF8(); <br>var txtCbd = window.clipboardData.getData("Text"); <br>var iCbdLen = txtCbd.lenUTF8(); <br>if((iMaxLen - iTxtLen) <= iCbdLen) { <BR>var iSurplusLen = iMaxLen - iTxtLen; <BR>var subStr = txtCbd.substr(0, iSurplusLen); <BR>var insertStr = ''; <BR>for(var i = 0; i < subStr.length; i  ) { <BR>var chr = subStr.substr(i, 1); <BR>if(iSurplusLen >= chr.lenUTF8()) { <br>insertStr  = chr; <br>iSurplusLen -= chr.lenUTF8(); <br>} <br>} <br><br>Inputs.AddOnPos(_this, insertStr); <br>//_this.style.backgroundColor = 'red'; <br>//System.setTimeout(Inputs.ColorTips, 500, _this); <br>event.returnValue = false; <br>event.srcElement.style.imeMode = 'disabled'; <br>} else { <br>event.returnValue = true; <br>event.srcElement.style.imeMode = 'auto'; <br>} <br>} break; <br><br>case 'keypress': { <br>var iTxtLen = _this.value.lenUTF8(); <br>if(iMaxLen <= iTxtLen) { <BR>while(_this.value.lenUTF8() > iMaxLen) { <br>_this.value = _this.value.substr(0, _this.value.length - 1); <br>} <br>Inputs.DisableInput(event); <br>if('disabled' != event.srcElement.style.imeMode) { <br>event.srcElement.style.imeMode = 'disabled'; <br>} <br>} <br>else { <br>if('auto' != event.srcElement.style.imeMode) { <br>event.srcElement.style.imeMode = 'auto'; <br>} <br>} <br>} break; <br><br>case 'keyup': { <br>var k = System.isIE ? event.keyCode : event.which; <br><br>if (8 != k <br>&& 9 != k <br>&& 46 != k <br>&& 37 != k <br>&& 39 != k <br>&& 16 != k <br>&& 36 != k <br>&& 35 != k <br>&& 17 != k <br>&& 13 != k <br>&& 189 != k <br>&& 187 != k <br>) { <br>if(_this.getAttribute) { <br>_this.fireEvent('onkeypress'); <br>} <br>} <br>} break; <br><br>case 'keydown': { <br>var k = System.isIE ? event.keyCode : event.which; <br><br>if (8 != k <br>&& 9 != k <br>&& 46 != k <br>&& 37 != k <br>&& 39 != k <br>&& 16 != k <br>&& 36 != k <br>&& 35 != k <br>&& 17 != k <br>&& 13 != k <br>&& 189 != k <br>&& 187 != k <br>) { <br>var iTxtLen = _this.value.lenUTF8(); <br>if(iMaxLen <= iTxtLen) { <BR>Inputs.DisableInput(event); <BR>} <BR>} <BR>} break; <BR>} <BR>}, <br><br>TextAreaMaxLength: function() { <br><br>var aX = document.getElementsByTagName('textarea'); <BR>for(var i = 0; i < aX.length; i  ) { <BR>if(aX[i].getAttribute('maxlength')) { <BR>aX[i].detachEvent('onbeforepaste', Inputs.MaxLength); <BR>aX[i].detachEvent('onpaste', Inputs.MaxLength); <BR>aX[i].detachEvent('onkeypress', Inputs.MaxLength); <BR>aX[i].detachEvent('onkeyup', Inputs.MaxLength); <BR>aX[i].detachEvent('onkeydown', Inputs.MaxLength); <br><br>aX[i].attachEvent('onbeforepaste', Inputs.MaxLength); <BR>aX[i].attachEvent('onpaste', Inputs.MaxLength); <BR>aX[i].attachEvent('onkeypress', Inputs.MaxLength); <BR>aX[i].attachEvent('onkeyup', Inputs.MaxLength); <BR>aX[i].attachEvent('onkeydown', Inputs.MaxLength); <BR>/* <BR>var res = 'zh-cn' == window.navigator.systemLanguage <BR>? '最大长度：' <BR>: 'Maximum length for: '; <br><br>if('' == aX[i].title) aX[i].title = res   aX[i].getAttribute('maxlength'); <BR>*/ <BR>} <BR>} <BR>}, <br><br>TextBoxMaxLength: function() { <BR>var aX = document.getElementsByTagName('input'); <BR>for(var i = 0; i < aX.length; i  ) { <BR>var maxLen = aX[i].getAttribute('maxlength'); <BR>if('text' == aX[i].type <BR>&& null != maxLen <BR>&& '' != maxLen <BR>&& undefined != maxLen <BR>&& 2147483647 > parseInt(maxLen) <br>&& '' == aX[i].title) { <br><br>aX[i].detachEvent('onbeforepaste', Inputs.MaxLength); <br>aX[i].detachEvent('onpaste', Inputs.MaxLength); <br>aX[i].detachEvent('onkeypress', Inputs.MaxLength); <br>aX[i].detachEvent('onkeyup', Inputs.MaxLength); <br><br>aX[i].attachEvent('onbeforepaste', Inputs.MaxLength); <br>aX[i].attachEvent('onpaste', Inputs.MaxLength); <br>aX[i].attachEvent('onkeypress', Inputs.MaxLength); <br>aX[i].attachEvent('onkeyup', Inputs.MaxLength); <br>/* <br>var res = 'zh-cn' == window.navigator.systemLanguage <br>? '最大长度：' <br>: 'Maximum length for: '; <br><br>aX[i].title = res   aX[i].getAttribute('maxlength'); <br>*/ <br>} <br>} <br>} <br>} <br><br>Tools.Inputs = Inputs; <br><br>window.attachEvent('onload', Tools.Inputs.TextAreaMaxLength); <br>window.attachEvent('onload', Tools.Inputs.TextBoxMaxLength);<br>
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