I am creating a random photo365 challenge list generator using javascript. I have a list of 365 different function which come up with a different assignment name/page link (this probably isn't the best way to do it, but it works)
It works as it's supposed to, it does call 365 functions and puts them in a list...
But what I'd like to do is prevent repeats. (Please note, the code below doesn't have all the 365 functions listed)
I have searched on stack overflow, and I have come across a variety of methods of preventing repeats. But any time I try to add the new code it, I can't get it to work.
I'm really not that skilled in javascript, so any guidance you could provide would be extremely appreciated...
Noel
//Create a new To-Do
function randomFrom(array) {return array[Math.floor(Math.random() * array.length)];}
function randomCreate() {
var func = randomFrom([createNew365ToDo,
createNew365ToDoBulb,
createNew365ToDo2,
createNew365ToDoShallow,
createNew365ToDoWide,
createNew365ToDoLenses,
createNew365ToDoMacro,
createNew365ToDoAToZ]);
(func)();
}
function createNew365ToDoList()
{
deleteAll365Rows();
for (var p = 0; p < 365; p++) {
{
randomCreate();
}
}}
I would do something like this:
//are arrays passed by reference? I don't remember, so let's just make it available to everything to demonstrate
var fnArray = [createNew365ToDo, createNew365ToDoBulb, createNew365ToDo2, createNew365ToDoShallow, createNew365ToDoWide, createNew365ToDoLenses, createNew365ToDoMacro,createNew365ToDoAToZ];
function randomFunction() {
//get a random index from the list
var index = Math.floor(Math.random() * fnArray.length);
//save that function to fn, and REMOVE it from the list
var fn = fnArray.splice(index, 1);
//return that function - now, when randomFunction() gets called again, you won't ever
//return the same function since it's no longer in the list
return fn;
}
function callRandomFunction() {
var func = randomFunction();
(func)();
}
Related
The problem: I want to call a value from a nested method outside of its parent method. In other words, I want the output from "console.log(someObjects[i].valueChecker);" to be either "true" or "false." However, it is just returning the function itself.
What I've done so far: So I have been scouring the web/stack overflow for a solution, but either I haven't found a solution, or I just can't make sense of it. I think it has something to do with "closures," and most of the solutions to problems I've seen have been to return from the submethod, and then return the submethod from the parent method. However, every time I've tried this, I've just encountered numerous errors-- either another submethod suddenly doesn't exist, or the code runs, but the output is still a function. I wonder if having multiple methods affects the issue.
Context: I'm making a platformer game, and there are multiple types of the same enemy. I want to check for collision between the player and weapon and thusly need some values from the enemy function (I don't want to use the word "class," but I'm not sure about the appropriate terminology). I'm much more familiar with Java though, so it is frustrating me to not be able to create a separate class and just have a method to give me values back.
//assume all the other html/main stuff is already set up
var temp = {
create: c4,
update: u4
}
MyObject = function(value) {
this.value = value; //passed in value
var magicNumber = 4; //local value initialized/declared
this.valueChecker = function() {
//return boolean
return this.value == this.magicNumber;
}
this.otherValueChecker = function() {
//return boolean
return (this.value + 1) == this.magicNumber;
}
}
//just make the space bar tied to a boolean
var someKeyPress;
function c4() {
someKeyPress = game.input.keyboard.addKey(Phaser.Keyboard.A);
}
var someObjects = [];
//... later on in the program, presuming key already coded
function u4() {
//add a new MyObject to array someObjects
if (someKeyPress.isDown) {
//check with various random numbers between 3 to 5
someObjects.push(new MyObject(game.rnd.integerInRange(3, 5)));
}
//run through MyObject(s) added to someObjects, and see if any match number
for (var i = 0; i < someObjects.length; i++) {
console.log(someObjects[i].valueChecker);
}
}
/* current output
ƒ () {
//return boolean
return this.value == this.magicNumber;
}
*/
Try
console.log(someObjects[i].valueChecker())
Because I see the value checker as a function
this.valueChecker = function()
I'm struggling to get my head around invoked functions and their usage. I have a function called addExp - it adds experience points to the player object and determines whether or not the player has levelled up.
Here is the function:
function addExp(amt) {
return function(amt) {
player.exp += amt;
while(player.exp >= player.reqExp) {
var carry = player.exp - player.reqExp;
player.level++;
nextLevel(player.level);
player.exp = 0 + carry;
}
}
}
Here is what happens when I use it:
addExp(200); // adds no exp to the player
addExp(200)(200); // adds 200 exp to the player
addExp()(200); // adds 200 exp to the player
I have searched around online and read other questions but can't understand why it works like this - which (if any) of those function calls is done correctly? Could someone please explain, in simple enough terms, why returning a function within a function is advantageous?
I've been trying to implement some card game using Javascript. In the snippet below, I simply want to pull two cards from the top of the deck and give it to the player (simplified logic below)
function deck() {
var faceCards = [['jack', 11],['queen', 12],['king', 13]];
return faceCards;
}
function removeCard() {
var singleCard = deck().pop();
var faceValue = singleCard[0];
return faceValue;
}
var cardPair = [removeCard(),removeCard()];
console.log(cardPair);
However the faceCards array is still the same even after popping off its cards which means that the next card will be the same as well as seen in cardPair array.
I need to mirror the effects I used inside of the
removeCard() function to reflect back in the deck() function.
I suppose I could either create the faceCards array in the global scope or use 'this' in some way (which I don't really want as I'm not much familiar with it). How can I update one function from inside another function? Thank you very much for reading this.
Your error is here:
var singleCard = deck().pop()
The call to deck() creates a new array of cards every time it's called, and doesn't repeatedly return the same array.
If you don't want to go full OO yet, consider at least passing the deck as a parameter to the removeCard() function, i.e.
function removeCard(deck) {
var singleCard = deck.pop();
var faceValue = singleCard[0];
return faceValue;
}
var deck = newDeck();
var pair = [ removeCard(deck), removeCard(deck) ];
but ultimately you should longer term be going for a full OO solution, where your usage might then become:
var deck = new Deck();
var pair = [ deck.takeCard(), deck.takeCard() ];
implementation of this is out of scope of this particular question.
You're creating a new array every time you run deck(). Try saving the deck in an array and running pop on this:
function deck() {
var faceCards = [['jack', 11],['queen', 12],['king', 13]];
return faceCards;
}
function removeCard(fromDeck) {
var singleCard = fromDeck.pop();
var faceValue = singleCard[0];
return faceValue;
}
var thisDeck = deck();
var cardPair = [removeCard(thisDeck),removeCard(thisDeck)];
console.log(cardPair);
I am working on learning JavaScript composition over inheritance and I am struggling with a few concepts. One being, the game presents users with a random number of dogs, they are then prompted to enter how many there are.
If they get it correct, they score a point and are then presented with another number of dogs.
The thing I can't work out is how to generate new dogs each time. The below code is the simplified code setup:
var dog = function dog(state) {
return {
create: function create() {
console.log('Create the dogs');
this.dogIsCreated();
},
dogIsCreated: function dogIsCreated() {
console.log('How many dogs do you see?');
}
}
}
var questionOne = dog({number: 3}).create();
Once they have chosen the right number, i need to effectively call:
var questionTwo = dog({number: 6}).create();
The number itself will just be a call to a random number generator, but how would I call questionTwo automatically? I have no idea where to even begin!
Many thanks!
The action of 'getting it correct' occurs because of an event. You need to hook into this event, determine true/false, and when correct call dog({number: x}).create();.
If your requirement is more complex than this, please clarify your question. Thanks.
Approach this using array should provide better accessibility.
var dog = function dog(state) {
return {
answer: state.number,
create: function create() {
console.log('Create the dogs');
this.dogIsCreated();
},
dogIsCreated: function dogIsCreated() {
console.log('How many dogs do you see?');
}
}
var currentQuestion = 0;
var question = [];
function nextQuestion() {
if (currentQuestion > 0) {
//to access the last question use question[currentQuestion] e.g. question[currentQuestion].answer
}
question.push(dog({number: 6}).create());
currentQuestion++;
}
If I have an array of objects is there any way possible for the item to splice itself out of the array that contains it?
For example: If a bad guy dies he will splice himself out of the array of active enemies.
I probably sound crazy but that ability would simplify my code dramatically, so I hope for something cool =)
The way you would do it is as follows:
var game_state = { active_enemies: [] };
function Enemy() {
// Various enemy-specific things go here
}
Enemy.prototype.remove = function() {
// NOTE: indexOf is not supported in all browsers (IE < 8 most importantly)
// You will probably either want to use a shim like es5-shim.js
// or a utility belt like Underscore.js
var i = game_state.active_enemies.indexOf(this);
game_state.active_enemies.splice(i, 1);
}
See:
Es5-Shim
Underscore.js
Notta bene: There are a couple of issues here with this manner of handling game state. Make sure you are consistent (i.e. don't have enemies remove themselves from the list of active enemies, but heroes remove enemies from the map). It will also make things more difficult to comprehend as the code gets more complex (your Enemy not only is an in-game enemy, but also a map state manager, but it's probably not the only map state manager. When you want to make changes to how you manage map state, you want to make sure that code is structured in such a way that you only need to change it in one place [preferably]).
Assuming the bad guy knows what list he's in, why not?
BadGuy.prototype.die = function()
{
activeEnemies.splice(activeEnemies.indexOf(this), 1);
}
By the way, for older browsers to use indexOf on Arrays, you'll need to add it manually.
You kind of want to avoid circular references
I would suggest creating an object/class that represents the active enemies list. Create methods on that instance for adding/removing a given item from the list - abstracting the inner workings of the data structure from the outside world. If the active enemies list is global (e.g. there's only one of them), then you can just reference it directly to call the remove function when you die. If it's not global, then you'll have to give each item a reference to the list so it can call the function to remove itself.
You can also use an object and instead of splice, delete the enemy:
var activeEnemies = {};
function Enemy() {
this.id = Enemy.getId(); // function to return unique id
activeEnemies[this.id] = this;
// ....
}
Enemy.getId = (function() {
var count = 0;
return function() {
return 'enemyNumber' + count++;
}
}());
Enemy.prototype.exterminate = function() {
// do tidy up
delete activeEnemies[this.id];
}
Enemy.prototype.showId = function() {
console.log(this.id);
}
Enemy.prototype.showEnemies = function() {
var enemyList = [];
for (var enemy in activeEnemies) {
if (activeEnemies.hasOwnProperty(enemy)) {
enemyList.push(enemy);
}
}
return enemyList.join('\n');
}
var e0 = new Enemy();
var e1 = new Enemy();
console.log( Enemy.prototype.showEnemies() ); // enemyNumber0
// enemyNumber1
e0.exterminate();
console.log( Enemy.prototype.showEnemies() ); // enemyNumber1