html运行实例（eg_js_function_parameter

代码示例：（标识：eg_js_function_parameter_default）

<!DOCTYPE html>
<html>
<body>

<h1>将默认值设置为函数参数</h1>

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

<script>
function myFunction(x, y) {
  if (y === undefined) {
    y = 0;
  }  
  return x * y;
}
document.getElementById("demo").innerHTML = myFunction(4);
</script>

</body>
</html>