当获焦时,文本消失,失焦时文本出现
<!doctype html><html><head><meta charset="utf-8"><title>无标题文档</title></head><body><input id="text" type="text" value="点我就消失"/><script>var oText=document.getElementById("text");var onoff=true;oText.color="#000";oText.onfocus=function(){if(onoff){this.value="";this.color="red";onoff=false;}}oText.onblur=function(){if(this.value==''){this.color="#000";this.value="点我就消失";onoff=true;}}</script></body></html>