让我们采用一个简单的表达式“ 4 + 5等于9”。这里4和5称为操作数，“ +”称为运算符。
JavaScript支持以下类型的运算符。
算术运算符
比较运算符
逻辑（或关系）运算符
赋值运算符
条件（或三元）运算符
这是一个说明运算符示例的示例-
<html>
<body>
<script>
var a = 33;
var b = 10;
var c = "Test";
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>