js控制一个文本域输入数字长短

 

第一种实现

jsp代码

 

<form action="" name="myForm">
<div class="pl_box"><textarea  name="textarea" class="textarea_2"
    disabled="" onKeyDown="textCounter(this.form.textarea,this.form.remLen,100);"
 onKeyUp="textCounter(this.form.textarea,this.form.remLen,100);"></textarea>
 </div>
<div id="showErrorDiv" style="font-size: 13px; color: red;">
     您最多可以输入:<input name="remLen" type="text"
value="100" size="5" readonly="readonly" disabled="disabled">个字符 
</div>
</form>
<div class="pl_btn"><a href="#" class="link1"
    onclick="publishComent('${username}')">发表评论</a></div>

 

 

 

js代码

 

function textCounter(field, countfield, maxlimit) {  
    // 函数，3个参数，表单名字，表单域元素名，限制字符；   
    if (field.value.length > maxlimit){
        //如果元素区字符数大于最大字符数，按照最大字符数截断；   
        field.value = field.value.substring(0, maxlimit);
    }
    else   
    //在记数区文本框内显示剩余的字符数；   
    countfield.value = maxlimit - field.value.length;   
    }

 

 第二种实现

 

jsp代码

<div class="pl_box">
                    <textarea name="textarea" class="textarea_2" disabled=""  onfocus="fed_inputMaxLength(this,100,'catchask_con_counter_num')"></textarea>
                </div>
                <div class="textarea_con_counter">请发表您的观点评论内容，您还能输入<strong id="catchask_con_counter_num"  class="catchask_con_counter_num" >100</strong>字。
                    <span id="textareaError" class="textarea_con_textareaError"></span>
                </div>

 

 

 

js代码：

 

  
    function fed_inputMaxLength(target,maxlength,counterId){ 
        if($(target).attr('fed_max_length')==null){ 
            $(target).attr('fed_max_length',maxlength); 
            var counter = $('#'+counterId); 
            if ($.browser.msie) { //IE
                $(target).unbind("propertychange").bind("propertychange", function(e) { 
                    e.preventDefault(); 
                    textareaMaxProc1(target, maxlength); 
                    counter.html(maxlength-$(target).val().length); 
                }); 
                target.attachEvent("onpropertychange", function(e) { 
                    //e.preventDefault(); 
                    textareaMaxProc1(target, maxlength); 
                    counter.html(maxlength-$(target).val().length); 
                }); 
               
            }else {
                target.addEventListener("input",function(e) { 
                    e.preventDefault(); 
                    textareaMaxProc1(target, maxlength); 
                    counter.html(maxlength-$(target).val().length); 
                },false);  
            } 
            $('target').unbind("keypress").bind("keypress", function(event) { 
                var code; 
                if(typeof event.charCode =="number" ){  
                    code = event.charCode; 
                }else{ 
                    code = event.keyCode; 
                } 
                if(code > 9 && !event.ctrlKey && $(target).val().length>=maxlength){ 
                    event.preventDefault(); 
                }else if(event.ctrlKey && $(target).val().length>=maxlength && code==118){ 
                    event.preventDefault(); 
                } 
            }); 
        } 
    } 
     
      
    function textareaMaxProc1(textArea, total){ 
        var max; 
        max=total; 
         
        if($(textArea).val().length > max){ 
            $(textArea).val($(textArea).val().substring(0,max)); 
        } 
    }