<!DOCTYPEhtml><htmllang="en"><head><metacharset="UTF-8"><metaname="viewport"content="width=device-width, initial-scale=1.0"><metahttp-equiv="X-UA-Compatible"content="ie=edge"><title>Document</title><style>input {
color: #999; }
</style></head><body><inputtype="text"value="手机"><script>vartext=document.querySelector('input');
text.onfocus=function() {
if (this.value==='手机') {
this.value='';
}
this.style.color='#333';
}
text.onblur=function() {
if (this.value==='') {
this.value='手机';
}
this.style.color='#999';
}
</script></body></html>
