本文實(shí)例講述了JS與jQuery判斷文本框還剩多少字符可以輸入的方法。分享給大家供大家參考，具體如下：
javascript部分：
function $(id) { return document.getElementById(id);}var maxLen=255;function checkMaxInput(){ if($("summary").value.length>maxLen){ $("summary").value=$("summary").value.substring(0,maxLen); }else{ $("leaves").innerHTML=maxLen-$("summary").value.length; }}HTML部分：
<tr> <td>摘要：</td> <td> <html:textarea property="summary" rows="5" cols="60" onkeyup="checkMaxInput()"/> <br> 還可以輸入<span class="red" id="leaves">255</span>個(gè)字符 </td></tr>
jQuery插件textlimit實(shí)現(xiàn)Javascript統(tǒng)計(jì)和限制字符個(gè)數(shù)功能
使用jQuery插件textlimit可以實(shí)現(xiàn)統(tǒng)計(jì)和限制字符個(gè)數(shù)功能，可應(yīng)用于文本框與文本區(qū)域，當(dāng)輸入文字時(shí)textlimit插件會(huì)及時(shí)統(tǒng)計(jì)當(dāng)前文本框與文本區(qū)域中的字符個(gè)數(shù)，如果達(dá)到限制數(shù)則不允許輸入，同時(shí)可設(shè)置字符刪除速度，
使用實(shí)例
一、包含文件部分
<script type="text/javascript" src="jquery.js"></script><script type="text/javascript" src="textlimit.js"></script>
二、HTML部分
<input type="text" name="test" value="" id="test" /><span>20</span>/256
三、Javascript部分
<script type="text/javascript">jQuery(document).ready(function(){jQuery("#test").textlimit("span",256);});</script>當(dāng)在ID為test的文本框中輸入文字時(shí)，textlimit插件統(tǒng)計(jì)當(dāng)前輸入字符個(gè)數(shù)并顯示在一個(gè)span的元素中，如上效果圖，textlimit接口如下：
textlimit(counter_el, thelimit, speed)
接口參數(shù)說明：
注意：英文字符與漢字字符都統(tǒng)計(jì)為一個(gè)字符
textlimit插件統(tǒng)計(jì)和限制字符數(shù)非常簡(jiǎn)單，具體大家可以看看textlimit的庫(kù)文件，非常值得推薦。
/* * TextLimit - jQuery plugin for counting and limiting characters for input and textarea fields * * pass '-1' as speed if you don't want the char-deletion effect. (don't just put 0) * Example: jQuery("Textarea").textlimit('span.counter',256) * * $Version: 2009.07.25 +r2 * Copyright (c) 2009 Yair Even-Or * vsync.design@gmail.com*/(function(jQuery) { jQuery.fn.textlimit=function(counter_el, thelimit, speed) { var charDelSpeed = speed || 15; var toggleCharDel = speed != -1; var toggleTrim = true; var that = this[0]; var isCtrl = false; updateCounter(); function updateCounter(){ if(typeof that == "object") jQuery(counter_el).text(thelimit - that.value.length+" characters remaining"); }; this.keydown (function(e){ if(e.which == 17) isCtrl = true; var ctrl_a = (e.which == 65 && isCtrl == true) ? true : false; // detect and allow CTRL + A selects all. var ctrl_v = (e.which == 86 && isCtrl == true) ? true : false; // detect and allow CTRL + V paste. // 8 is 'backspace' and 46 is 'delete' if( this.value.length >= thelimit && e.which != '8' && e.which != '46' && ctrl_a == false && ctrl_v == false) e.preventDefault(); }) .keyup (function(e){ updateCounter(); if(e.which == 17) isCtrl=false; if( this.value.length >= thelimit && toggleTrim ){ if(toggleCharDel){ // first, trim the text a bit so the char trimming won't take forever // Also check if there are more than 10 extra chars, then trim. just in case. if ( (this.value.length - thelimit) > 10 ) that.value = that.value.substr(0,thelimit+100); var init = setInterval ( function(){ if( that.value.length <= thelimit ){ init = clearInterval(init); updateCounter() } else{ // deleting extra chars (one by one) that.value = that.value.substring(0,that.value.length-1); jQuery(counter_el).text('Trimming... '+(thelimit - that.value.length)); } } ,charDelSpeed ); } else this.value = that.value.substr(0,thelimit); } }); };})(jQuery);希望本文所述對(duì)大家JavaScript程序設(shè)計(jì)有所幫助。
新聞熱點(diǎn)
疑難解答
