当我尝试在html页面中查看我的变量之一时，我什么也没看到。如果打开控制台，则会看到此错误
未捕获的TypeError：无法在my-java-script.js：17上将属性'innerHTML'设置为null。
我的脚本很简单。以下是代码：my-java-script.js：
var c = 3+4;
console.log(“The value of c is”, c);
var x=6 ;
var y=3;
var s = x-y ;
console.log(“Subtraction of” , x , “and” , y , “is”, s);
var m = x*y ;
console.log(“Multiplication of”, x , “and” , y , “is”, m);
var a = x+y ;
console.log(“Addition of”, x , “and” , y , “is”, a);
var d = x/y ;
console.log(“Division of”, x , “and” , y , “is”, d);
var ao = (x*y +10)/4;
console.log(ao);
var myVariable = “HELLO”;
document.getElementById(“demo”).innerHTML = myVariable;
my-java-webpage.html：
<!DOCTYPE html>
<html>
<head>
<title>Java Webpage </title>
<script type="text/javascript" src = "my-java-script.js"></script>
</head>
<body>
<h1> Java script</h1>
<p id="demo"></p>
</body>
</html>
以下是控制台和网页的图片： pic of the console and the webpage:
这是因为“”未正确使用，还尝试使用刚关闭的正文中的脚本
var c = 3+4;
console.log("The value of c is", c);
var x=6 ;
var y=3;
var s = x-y ;
console.log("Subtraction of" , x , "and" , y , "is", s);
var m = x*y ;
console.log("Multiplication of", x , "and" , y , "is", m);
var a = x+y ;
console.log("Addition of", x , "and" , y , "is", a);
var d = x/y ;
console.log("Division of", x , "and" , y , "is", d);
var ao = (x*y +10)/4;
console.log(ao);
var myVariable = "HELLO";
document.getElementById("demo").innerHTML = myVariable;<!DOCTYPE >
<html>
<head>
<title>Avengers Avenue</title>
</head>
<body>
<h1>Java script</h1>
<p id="demo"></p>
<script type="text/javascript" src = "my-java-script.js"></script>
</body>
</html>