<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Title</title> </head> <body> <h1 id="demo1"></h1> <h1 id="demo2"></h1> <script> var person = { firstName: "John", lastName : "Doe", id : 5566, fullName : function() { return this.firstName + " " + this.lastName; } }; document.getElementById("demo1").innerHTML = "不加括号