Is there a way to reliably delete/wipe a variable

Today crypto libraries for JavaScript exists sjcl and hence there may be the situation that a password/key/secret/sensitivedata is stored somewhere in a variable in JavaScript.

I do not want to risk that this sensitve data is leaked/disclosed and hence I would very much like to know if there is a way to reliably wipe a variable in Javascript so that the memory used by the JavaScript Engine will not have any remaining info about he data? I would for instance not want to rely on some GC to wipe the data lazily etc.

An answer might feature an example code that kills/wipes a variable and also an explanation when (and if there are differences on what JavaScript implementation Browsers type /Nodejs) it makes sence to trust that the data has been deleted?

Else if the task is impossible I would appreciate a explanation why this is so as well and also accept this as an answer

The goal is not to protect the webpage user from accessing the script variable (this cannot be done I guess). The goal is more to guarantee that the memory of the javascript engine does not keep shadow/cached copies of the data, after the point necessary. I do want to have the data be gone so that no-one (attacker software) can get the secret data via looking at the memory been associated with the Javascript Variables.

JavaScript is garbage collected. In addition, there is no mechanism for deterministic resource management built in. You can make one, but the resource would have to be external.

Even if you build such a mechanism (with a C++ external module in Node for example), engines don't give you strong guarantees on when their copy of the memory is cleared. You would have to manually assign to the same variable parts of the resource data and replace it with junk yourself. That would likely work but there is still no guarantee at the engine level.

This is simply not a problem JavaScript implementations are built to do well at this point. There is no SecureString. That said - smart people are working on variants of ECMAScript (the JS standard) that give you much stronger guarantees. That's a good first step towards addressing the problem (but no such guarantee yet).

I don't even want to get started on browsers, where browser extensions can easily get better hooks than you and write over Function.prototype.call and hook on every function call, JavaScript has quite powerful AOP capabilities built in, for worse in this instance.

One possible solution would be to run the whole program within a VM that uses encrypted RAM, but I'm against rolling your own crypto like that. Generally, an attacker should not have access to your program's RAM in the first place, if they do, they can install a browser extension :)