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181 lines
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ReStructuredText
181 lines
7.2 KiB
ReStructuredText
.. _netscriptjs:
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NetscriptJS (Netscript 2.0)
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===========================
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Netscript 2.0, or Netscript JS, is the new and improved version of Netscript that
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allows users to write (almost) full-fledged Javascript code in their scripts, while
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still being able to access the Netscript functions.
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NetscriptJS was developed primarily by `Github user jaguilar <https://github.com/jaguilar>`_
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On top of having almost all of the features and capabilities of JavaScript, NetscriptJS is also
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significantly faster than Netscript 1.0.
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This documentation will not go over any of the additional features of NetscriptJS, since
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there is plenty of documentation on Javascript available on the web.
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Browser compatibility
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---------------------
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As of the time of writing this, a few browsers do not support `dynamic import <https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/import>`_ functionality and therefore cannot run NetscriptJS scripts. These browsers will thus only be capable of using Netscript 1.0.
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How to use NetscriptJS
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----------------------
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Working with NetscriptJS scripts is the same as Netscript 1.0 scripts. The only difference
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is that NetscriptJS scripts use the ".ns" or ".js" extension rather than ".script". E.g.::
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$ nano foo.ns
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$ run foo.ns -t 100 arg1 arg2 arg3
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exec("foo.ns", "purchasedServer1", "100", "randomArg");
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The caveat when using NetscriptJS to write scripts is that your code must be
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asynchronous. Furthermore, instead of using the global scope and executing your code
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sequentially, NetscriptJS uses a :code:`main()` function as an entry point.
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Furthermore, the "Netscript environment" must be passed into a NetscriptJS script through
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the main function. This environment includes all of the pre-defined Netscript functions
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(:code:`hack()`, :code:`exec`, etc.) as well as the arguments you pass to the script.
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Therefore, the signature of the :code:`main()` function must be::
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export async function main(ns) {
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ns.print("Starting script here");
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await ns.hack("foodnstuff"); //Use Netscript hack function
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ns.print(ns.args); //The script arguments must be prefaced with ns as well
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}
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Here is a summary of all rules you need to follow when writing Netscript JS code:
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* Write :code:`await` before any call to the following Netscript functions:
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* hack
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* grow
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* weaken
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* sleep
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* prompt
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* wget
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* Any function that contains :code:`await` must be declared as :code:`async`
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* Always :code:`await` any function that is marked as :code:`async`
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* Any functions that you want to be visible from other scripts must be marked with :code:`export`.
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* **Do not write any infinite loops without using a** :code:`sleep` **or one of the timed Netscript functions like** :code:`hack`. Doing so will crash your game.
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* Any global variable declared in a NetscriptJS script is shared between all instances of that
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script. For example, assume you write a script *foo.ns* and declared a global variable like so::
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//foo.ns
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let globalVariable;
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export async function main(ns) {
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globalVariable = ns.args.length;
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while(true) {
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ns.tprint(globalVariable);
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await ns.sleep(3000);
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}
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}
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Then, you ran multiple instances of *foo.ns*::
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$ run foo.ns 1
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$ run foo.ns 1 2 3
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$ run foo.ns 1 2 3 4 5
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Then all three instances of foo.ns will share the same instance of :code:`globalVariable`.
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(In this example, the value of :code:`globalVariable` will be set to 5 because the
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last instance of *foo.ns* to run has 5 arguments. This means that all three instances of
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the script will repeatedly print the value 5).
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These global variables can be thought of as `C++ static class members <https://www.tutorialspoint.com/cplusplus/cpp_static_members.htm>`_,
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where a NetscriptJS script is a class and a global variable is a static member within that class.
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Warnings
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--------
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The NetscriptJS evaluation engine works by converting your code into a blob URL and then
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using a dynamic import to load your code as a module. Every unique NetscriptJS script
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is loaded as its own module. This means that
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making a small edit to a NetscriptJS script results in a new module being generated.
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At this point, we have been unable to find a method for deleting modules from browsers so that
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they get garbage collected.
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The result is that these modules from NetscriptJS scripts accumulate in your browser,
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using memory that never gets released. Over time, this results in a memory-leak type
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situation that can slow down your computer.
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Therefore, there are two recommendations for those who decide to use NetscriptJS:
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1. Every now and then, close and re-open the game. This will clear all of the modules.
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To be safe, I recommend **completely** closing the game's tab and then re-opening it.
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Depending on your browser, a refresh or page reload does not always clear the modules.
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2. Only use NetscriptJS scripts when needed. It is very unlikely that NetscriptJS
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is needed for very simple scripts. By doing this, you will reduce the number of modules
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that are loaded.
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Examples
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--------
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**Script Scheduler (scriptScheduler.ns)**
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This script shows some of the new functionality that is available in NetscriptJS,
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including objects and object constructors, changing an object's prototype, and
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importing other NetscriptJS scripts::
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import {tprintColored} from "tprintColored.ns"; //Importing from other NetscriptJS scripts works!
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function ScriptJob(params) {
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if (params.fn == null) {
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throw new Error("No Filename (fn) passed into ScriptJob ctor");
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}
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this.fn = params.fn;
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this.threads = params.threads ? params.threads : 1;
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this.args = params.args ? params.args : [];
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}
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ScriptJob.prototype.run = function(ns) {
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let runArgs = [this.fn, this.threads].concat(this.args);
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if (!ns.run.apply(this, runArgs)) {
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throw new Error("Unable to run " + this.fn + " on " +ns.getHostname());
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}
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tprintColored("Running " + this.fn + " on " + ns.getHostname(), "blue");
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}
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ScriptJob.prototype.exec = function(ns, target) {
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ns.scp(this.fn, target);
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let execArgs = [this.fn, target, this.threads].concat(this.args);
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if (!ns.exec.apply(this, execArgs)) {
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throw new Error("Unable to execute " + this.fn + " on " + target);
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}
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tprintColored("Executing " + this.fn + " on " + target, "blue");
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}
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export async function main(ns) {
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tprintColored("Starting scriptScheduler.ns", "red");
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try {
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let job = new ScriptJob({
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fn: "test.js",
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threads: 1,
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args: ["foodnstuff"]
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});
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job.run(ns);
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job.exec(ns, "foodnstuff");
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} catch (e) {
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ns.tprint("Exception thrown in scriptScheduler.ns: " + e);
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}
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}
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Final Note
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----------
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NetscriptJS opens up a lot of possibilities when scripting. I look forward to seeing
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the scripts that people come up with. Just remember that the power and capabilities of
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NetscriptJS come with risks. Please backup your save if you're going to experiment with
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NetscriptJS and report any serious exploits.
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With great power comes great responsibility
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Happy hacking
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