文本框失去焦点样式改变
<input type="text" value="" placeholder="请输入">
<script>
var input = document.querySelector('input');
// 获取焦点:onfocus
// 失去焦点:onblur
input.onblur = function() {
if(this.value==''){
this.style.background = 'pink';
}
}
</script>