js实现textarea的剩余字数动态提示效果demo

html:

<input name="title" type="text" size="50" value="{$p.title}" maxlength="15" onkeyup="javascript:setShowLength(this, 15, 'cost_tpl_title_length');"/><span class="red" id="cost_tpl_title_length">还可以输入15字数</span> 

js:

function setShowLength(obj, maxlength, id) { var rem = maxlength - obj.value.length; var wid = id; if (rem < 0){ rem = 0; } document.getElementById(wid).innerHTML = "还可以输入" + rem + "字数"; }