Merge pull request #1585 from danielyxie/dev

remove memory leak

doc/source/netscript/netscriptjs.rst

@@ -90,30 +90,6 @@ Here is a summary of all rules you need to follow when writing Netscript JS code
   These global variables can be thought of as `C++ static class members <https://www.tutorialspoint.com/cplusplus/cpp_static_members.htm>`_,
   where a NetscriptJS script is a class and a global variable is a static member within that class.
 
-Warnings
---------
-The NetscriptJS evaluation engine works by converting your code into a blob URL and then
-using a dynamic import to load your code as a module. Every unique NetscriptJS script
-is loaded as its own module. This means that
-making a small edit to a NetscriptJS script results in a new module being generated.
-
-At this point, we have been unable to find a method for deleting modules from browsers so that
-they get garbage collected.
-
-The result is that these modules from NetscriptJS scripts accumulate in your browser,
-using memory that never gets released. Over time, this results in a memory-leak type
-situation that can slow down your computer.
-
-Therefore, there are two recommendations for those who decide to use NetscriptJS:
-
-1. Every now and then, close and re-open the game. This will clear all of the modules.
-To be safe, I recommend **completely** closing the game's tab and then re-opening it.
-Depending on your browser, a refresh or page reload does not always clear the modules.
-
-2. Only use NetscriptJS scripts when needed. It is very unlikely that NetscriptJS
-is needed for very simple scripts. By doing this, you will reduce the number of modules
-that are loaded.
-
 Examples
 --------
 

src/NetscriptJSEvaluator.ts

@@ -19,6 +19,8 @@ export function compile(script: Script, scripts: Script[]): void {
   // by placing it inside an eval call.
   script.markUpdated();
   const uurls = _getScriptUrls(script, scripts, []);
+  if (script.url) URL.revokeObjectURL(script.url); // remove the old reference.
+  if (script.dependencies.length > 0) script.dependencies.forEach((dep) => URL.revokeObjectURL(dep.url));
   script.url = uurls[uurls.length - 1].url;
   script.module = new Promise((resolve) => resolve(eval("import(uurls[uurls.length - 1].url)")));
   script.dependencies = uurls;