Being someone who has spent literally decades interacting with CLIs on a near-daily basis, and who is also a huge fan of old text adventures, I wanted to see if a text-based game could be implemented in the browser's JavaScript console. ConsoleGame is my attempt to accomplish this.
Open the console in your browser's developer tools to check it out! (press F12).
There are several limitations of the browser console that made this project an interesting challenge. First, the console provides no way to directly read user input (I was hoping I could use process.argv like in Node, but alas!). This problem can be solved by implementing the commands available to the user as methods of the global object. Another small limitation is that user input cannot begin with numerals or many other characters because when used as property names, they cannot be accessed without using Object[propertyName] syntax, which will not work for our purposes.
However, this is not ideal, as the user would need to type the invocation operator after the command in order to invoke the function. The solution to this particular issue took me a while to find, but it was to assign the command functions to accessor properties (getters) instead of normal data properties of the global object. This allows the function to be called without the invocation operator.
As much as I would like to take credit for this clever solution, I borrowed it from Github user secretGeek (thank you!) who, I discovered, had already made such a game, which you can play here. While I was working on this project, Google also released a text adventure in the console, as an easter egg when you perform a search for "text adventure".
Another restriction I encountered is that only one-word commands will work, because the presence of any spaces in user input will throw a SyntaxError. Therefore, in order to implement a compound, two-word command, like "get lamp", the command words must be separated by either a carriage return or a semicolon. A further small inconvenience of this system is that user input cannot begin with numerals or many other characters because when used as property names, they cannot be accessed without using Object[propertyName] syntax, which will not work for our purposes.
It was was not immediately obvious to me how to relate an action and its object, because each was a separate function call, passed without any arguments. My solution was to maintain a global state, recording information about previous commands, and keeping a series of flags to be set by a command in order to change the program’s behavior with regard to subsequent commands.
For example, when a command represents an action (get) to be applied to an object, like a character or item (lamp), calling it will set a flag (objectMode = true) and store the name of the action (pendingAction = "get"), so that the next command will be interpreted as the object of the stored action.
The various action commands that involve objects are actually all only aliases of a single function, _act_upon, that sets the objectMode flag to true and assigns the name of the command to a variable, pendingAction. The function that will actually implement the action exists as a method on the target object (i.e. lamp.get()).
Any tasks that needed be performed every turn, like recording history and determining which commands will increment the turn counter, are executed by a function, turnDemon, that is bound to each command when it is set as an accessor property of the global object.
Valid commands are one word long, with no spaces. Compound commands consist of at most two commands, separated by a carriage return or a semicolon. For example:
get
What would you like to take?
lamp
You pick up the lamp.
or,
get;lamp
What would you like to take? You pick up the lamp.
When the game loads, you will be asked to type start to start a new game, resume if the history of a previous game persists in localStorage. You can type restore to load a previously saved game.
At any time once the game begins, typing inventory or i will display a list of any items the player is carrying. Typing look or l will give you a description of your current environs in the game.
In the game's current form, there are no prepositions, and look will only be used for this purpose, and not to "look at" something. Please instead use examine or its shortcut x instead. For example:
examine
What would you like to examine?
lamp
A battery-powered brass lantern is on the trophy case.
Because the game map consists of a multidimesional array of strings, it is gridlike by nature, and movement has therefore been restricted to the cardinal directions, north, south, east, and west, as well as up and down. These may be abbreviated as n, s, e, w, u and d, respectively.
You may save your game progress (it will be saved to localStorage) by typing save. You will then be asked to select a save slot, _0 through _9 (remember, user input can't begin with a number). Typing help will display the in-game help text.
Copyright © 2019 Dennis Hodges
The MIT License
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.