要执行JavaScript中的+，-，*等基本数学运算，请使用运算符。JavaScript包括基本数学运算符，例如加法，减法，乘法等。
您可以尝试运行以下代码，以学习如何使用基本数学，即JavaScript中的数学运算符-
<html>
<body>
<script>
var a = 77;
var b = 30;
var c = "Demo";
var linebreak = "<br />";
document.write("a + b = ");
result = a + b;
document.write(result);
document.write(linebreak);
document.write("a - b = ");
result = a - b;
document.write(result);
document.write(linebreak);
document.write("a / b = ");
result = a / b;
document.write(result);
document.write(linebreak);
document.write("a % b = ");
result = a % b;
document.write(result);
document.write(linebreak);
document.write("a + b + c = ");
result = a + b + c;
document.write(result);
document.write(linebreak);
a = ++a;
document.write("++a = ");
result = ++a;
document.write(result);
document.write(linebreak);
b = --b;
document.write("--b = ");
result = --b;
document.write(result);
document.write(linebreak);
</script>
</body>
</html>