Java String in Javascript function

Question

I want to pass a Java string variable to Javascript function which I am calling in Java code. Somehow the value of string remains as null. Is there any way to do this?

Here is some sample code

cb.set(CheckBox.ONCLICK,"displayCB(" + e.getFormName() + ",document.Profile.UniqueForm"+"_TestOpt)");

So in above line of code i am calling displayCB javascript function in generated Javascript code while my function for displayCB is like below:

sc.add("function displayCB(formname,field){"); sc.add("var str = formname + 'TestOption'"); ..

when I debug through firebug, I get str value as null

• Kaleb Brasee: How are you passing it, using JSTL and response properties? Please show the code.
• James Black: Are you passing the value in a response from the javascript, such as a json response? Javascript won't understand Java, but it does understand strings.
• Diodeus - James MacFarlane: Is the Java running on the server or the client?

Answer 1

try changing

cb.set(CheckBox.ONCLICK,"displayCB(" + e.getFormName() + ",document.Profile.UniqueForm"+"_TestOpt)");

to

cb.set(CheckBox.ONCLICK,"displayCB('" + e.getFormName() + "',document.Profile.UniqueForm"+"_TestOpt)");

The additional single quotes will make the script treat the value as a string literal instead of a variable name.

Answer 2

pass a Java string variable to Javascript function

Does this mean that:

• You're using JSP (server-side) to render values that are passed to JavaScript code which is executed on the client-side. This is not really calling between Java and JavaScript, more like generating JavaScript code with Java.

• You're really calling from Java to JavaScript, i.e using the JS runtime (Rhino?) in the JVM

Once you clarify this point, I'll try and help further. Also, please show the relevant code.

Update: It seems like the only possible reason why str is null is because the formname parameter of yout JS function is null. The value passed for this parameter (in code generated by the JSP) is e.getFormName().

• yogsma: Yes, you are right with first point. That's what I am doing. Here is some sample code cb.set(CheckBox.ONCLICK,"displayCB(" + e.getFormName() + ",document.Profile.UniqueForm"+"_TestOpt)"); So in above line of code i am calling displayCB javascript function in generated Javascript code while my function for displayCB is like below: sc.add("function displayCB(formname,field){"); sc.add("var str = formname + 'TestOption'"); .... when I debug through firebug, I get str value as null.
• Dónal: Can you please add this to your original post (use the edit button) and format it properly so I can actually read it
• yogsma: Don, I have checked its value and it is definitely not null.
• Dónal: Honestly, I think you should avoid this sort of code-generation. As you can see above, it makes it very difficult to see what's actually happening in the JS code