changing javascript variable using address bar

What I'm trying to do is change a javascript variable value in a website using the address bar. I've done this before, but can't seem to get it to work again. I can't remember how I did it. I know that it's worked before.

Example, on the site www.thewebsiteisdown.com, in the unix section, if the variable LOGIN_USER is set to root, you will receive different feedback for certain 'commands'. I try to set the variable to root by entering "javascript:LOGIN_USER=root" (without the quotation marks) into the address bar but the feedback doesn't change, so apparently it isn't changing the variable.

Like I said, I know that I've done this before, but can't remember the exact command that I used. Either something has changed that is preventing this from working, or I'm not entering it like I did before.

Another example.. Some website block certain functions like highlighting text using javascript.. Being able to enter javascript in the address bar, one should be able to negate these javascript functions. I can't get entering the javascript in the address bar to work in these cases, either.

 

Well, I suppose I figured it out... the following code works, at least in the first example.

javascript: var LOGIN_USER='root'