Javascript教程_JS检测 textarea 的问题教程_Javascript教程_H5之家

JS检测 textarea 的问题教程

<form method="get" action="#" >
<div class="iciba_left"><a href="" target="_blank"><img src="themes/skin/iciba/iciba.gif" /></a></div>
<div class="iciba_top_main">
<textarea name="iciba_doc" id="iciba_doc"></textarea>
</div>
<div class="iciba_right">
<input name="iciba_go" type="submit" value="" />
</div>
</form>

<script>
if(document.getElementById('iciba_doc').value==''){
document.getElementById('iciba_doc').value=='请输入要查询的英文单词或句子，按CTRL+ENTER';
}
</script>

我这样做的检测为什么没反应啊

教程网

//输入框的默认值
function def_value(id,msg){
    if(document.getElementById(id).value==""){
        document.getElementById(id).value=msg;
    }
    document.getElementById(id).onclick=function(){
        if(document.getElementById(id).value==msg){
            document.getElementById(this.id).value="";
        }
    }
    document.getElementById(id).onblur=function(){
        if(document.getElementById(id).value==''){
            document.getElementById(this.id).value=msg;
        }
    }
}

调用方法
<script>
window.onload=function(){
def_value('iciba_doc','请输入要查询的英文单词或句子，按CTRL+ENTER');
};
</script>