代码示例:(标识:eg_js_function_declaration)
<!DOCTYPE html>
<html>
<body>

<h1>JavaScript 函数</h1>

<p>此例调用一个执行计算并返回结果的函数:</p>

<p id="demo"></p>

<script>
var x = myFunction(4, 3);
document.getElementById("demo").innerHTML = x;

function myFunction(a, b) {
  return a * b;
}
</script>

</body>
</html>
运行结果: