How to create a html obejct with javascript in a jsp page

Question

all, I want to create a html obejct with javascript in a jsp page, but 'alert(GameObject1.loginurl);' will alert 'undefined'.

Do I get some misstakes in the code below? It seems that 'obj.appendChild' has failed.But Why?

var obj;
try {
obj = document.createElement("object");
obj.id = "GameObject1";
obj.name = "JavaGameObject1";
obj.setAttribute("classid", "clsid:72E6F181-D1B0-4C22-B0D7-4A0740EEAEF5");
obj.width = 640;
obj.height = 526;

var loginurl = document.createElement("param");
loginurl.setAttribute("name", "loginurl");
loginurl.setAttribute("value", "xx.xx.xx.xx:8080");
obj.appendChild(loginurl);

document.body.appendChild(obj);

alert(GameObject1.loginurl);
} catch (e) {
alert("Exception:" + e.message);
}

Answer 1

Based on your code, GameObject1 is never defined. I think you are wanting to use obj instead as that is the HTML object for the ID GameObject1.

I will note however that even obj.loginurl will still be undefined as you created the child HTML object param called loginurl, not a property to the HTML object obj. (ie. You would have needed to do obj.loginurl = "xx.xx.xx.xx:8080" to access it the way you seem to want)

To get the child element param's value, you would want something like obj.children[0].value which will return the value you set on your loginurl object. Alternatively, in your current scope you could just call loginurl.value.

When accessing child elements via obj.children[#], it is best to do checks to see if the element at that position exists so you don't throw exceptions everywhere.

Answer 2

To access the loginurl, you could use

alert(obj.getElementsByTagName("param")[0]);
alert(obj.getElementsByTagName("param")[0].name);
alert(obj.getElementsByTagName("param")[0].value);

Accessing like the way you mentioned is proper way of getting the attributes and not the child element.

GameObject1  // Will look for Object variable not the object with id "GameObject1" - You should use document.getElementById("GameObject1")
GameObject1.loginurl // will look for attribute and not the child element