<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta http-equiv="X-UA-Compatible" content="IE=edge"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <title>Document</title> <style> input{ color: #999; } </style> </head> <body> <input type="text" value="手机"> <script> //获取元素 程序处理 var input = document.querySelector(‘input‘); input.onfocus = function(){ if(this.value == "手机"){ this.value = ""; } //获得焦点时 让文本框中的值变成黑色 this.style.color = "#333"; } input.onblur = function(){ if(this.value == ""){ this.value = "手机"; } //失去焦点时 让文本框中的值变成浅色 this.style.color = "#999"; } </script> </body> </html>