Executing JavaScript from the address bar causes the browser to exit the page?

When you copy and paste the javascript: label into some browsers URL bars it automatically removes it. This is a security measure following certain attacks which have occurred in the past whereby people were asked to copy exploitative JavaScript into their URL bars in order for attackers to steal data.

If you want to execute JavaScript like this, you may find that you need to manually type out the javascript: part, otherwise your browser will assume that you're wanting to instead search for document.getElementById(...)....

Example

Copy the following into your address bar:

javascript:alert('hi');

For me, in Chrome on Windows, the javascript: part is removed and instead it assumes I want to search for alert('hi'):

A better solution

Depending on what you're trying to achieve, you'd probably be better off executing JavaScript through your browser's JavaScript console. If you're unsure how to do that, check this out: How to open the JavaScript console in different browsers?

One more solution:

javascript: (function(){ /* Your Javascript code goes here */ })();

Add a void(0); to the end and it will fix it.