问题
I am new to javascript and nodejs and I'm using this project to develop my skill and learn the new technologies. Currently my project uses multiple classes that depend on one another. The class files are in different directories and I am currently trying to use export and require statements to allow classes to be referenced in other files. I am also using browserify and watchify to bundle all the files together, to simplify the html script tag.
Here's Project Layout (JavaScript Folder)
-Base (Folder)
--Game.js (Class)
--Player.js (Class)
--Ball.js (Class)
-Helpers (Folder)
--Draw.js (Class)
--Helper.js (Class)
-GameType (Folder)
--Game1.js (Class)
The classes that are dependent on one another are as follows.
Game is Dependent on
--Draw.js
--Helper.js
Player and Ball are Dependent on
--Helper.js
Game1
--Game.js
--Ball.js
--Player.js
The project loads with in an app.js file, and requires the game1 file. At the moment I am trying to test and get all the require and export statements working. Currently with in the app.js file I am able to create a game1 object but I am unable to access the variables and methods with in it. I can console log the object and it has all the correct variables and methods, so it is creating the game1 object correctly, but I can't access any part of it. I am unsure if I am currently using the require and export statements incorrectly for the ES6 class notation, or if there is another problem with my code. Am I using the require and export statments correctly?
Here are the snippets on the classes and the app.js file. Some of the methods in a couple of the classes need to be finished, but I am trying to add in the require and export functionality to make the navigation of my code better. I hope you can help my find the solution to my problem.
app.js
const Game1 = require('./GameType/game1.js');
window.onload = function(){
console.log("Test Started");
console.log();
var canvasLocator = document.querySelector("#gameCanvas");
var canvasContext = canvasLocator.getContext("2d");
var game1 = new Game1();
//Prints out the correct object in the console
console.log(game1);
game1.draw();
//Returns an empty array of objects
//In my test is should return a draw obj
}
Game1.js
const Game = require('../Base/Game.js');
const Ball = require('../Base/Ball.js');
const Player = require('../Base/Player.js');
class Game1 extends Game{
constructor(){
super();
this.ball = new Ball(400, 300);
this.player1 = new Player("User", 15, 275, "blue");
this.player2 = new Player("AI", 775, 275, "blue");
this.mouseYPos;
}
refresh(){
//Needs to be implemented
}
draw(){
console.log("Super Draw: " + this.ball);
}
moveEverything(){
//Needs to be implemented
}
}
module.exports = Pong;
Game.js works as an interface and also has variables necessary to all games
'use strict';
const Helper = require('../Helpers/Helper.js');
const Draw = require('../Helpers/Draw.js');
class Game{
constructor(){
this.interval;
this.started = false;
this.framesPerSecond = 30;
this.drawObj = new Draw();
this.helper = new Helper();
}
//Each game needs to implement
draw(){
console.log("draw() not implemented in child class!");
}
moveEverything(){
console.log("moveEverything() not implemented in child class!");
}
refresh(){
console.log("refresh() not implemented in child class!");
}
};
module.exports = Game
Ball
const Helper = require('../Helpers/Helper.js')
class Ball{
constructor(x, y){
this.ballX = x;
this.ballY = y;
this.ballSpeedX;
this.ballSpeedY;
this.ballSpeedXChange;
this.ballSpeedYChange;
this.helper = new Helper();
}
move(x,y){
this.ballX = this.ballX + x;
this.ballY = this.ballY + y;
}
increaseSpeed(speedX, speedY){
this.ballSpeedX = this.ballSpeedX + speedX;
this.ballSpeedY = this.ballSpeedY + speedY;
}
reflectBall(player, drawObj){
}
reflect(ptOfContact, paddleSpeed){
}
setBallDifficulty(difficulty){
switch(difficulty){
case "Easy":
this.ballSpeedXChange = -1;
this.ballSpeedYChange = 1;
break;
case "Medium":
this.ballSpeedXChange = -1.5;
this.ballSpeedYChange = 1.5;
break;
case "Hard":
this.ballSpeedXChange = -2;
this.ballSpeedYChange = 2;
break;
default:
console.log("No difficulty Found");
}
}
}
module.exports = Ball
Player
const Helper = require('../Helpers/Helper.js');
class Player{
constructor(input, x, y, color){
//Boolean value for AI or Actual Player
this.inputType = this.inputType(input);
this.playerX = x;
this.playerY = y;
this.playerSpeed;
this.playerScore = 0;
this.paddleWidth = 10;
this.paddleHeight = 50;
this.color = color;
this.helper = new Helper();
}
move(drawObj){
//True: User Input
//False: AI Input
if(this.inputType){
this.movePlayerInYDir(drawObj);
}
else{
this.movePlayerAIInYDir(drawObj);
}
}
movePlayerInYDir(drawObj){
let before = this.playerY;
this.playerY = this.helper.playerInput(drawObj);
this.playerSpeed = this.playerY - before;
if((this.playerY + this.paddleHeight) >= (drawObj.getBaseHeight())){
this.playerY = (drawObj.getBaseHeight() - this.paddleHeight);
}
}
movePlayerAIInYDir(drawObj){
this.playerSpeed = this.setBotDifficulty("Easy");
this.playerY = this.playerY + this.playerSpeed;
if(this.playe2Y <= 0){
//Hits Top
this.playerSpeed = (this.playerSpeed) * -1;
}
else if((this.playerY + this.paddleHeight) >= drawObj.getBaseHeight()){
//Hits Bottom
this.playerSpeed = (this.playerSpeed) * -1;
}
}
setAIDifficulty(difficulty){
switch(difficulty){
case "Easy":
//TODO
break;
case "Medium":
//TODO
break;
case "Hard":
//TODO
break;
case "Practice":
//Unbeatable Mode
break;
default:
console.log("No difficulty Found");
}
}
//Helper
inputType(type){
//True: Real Input
//False: AI
switch(type){
case "User":
return true;
case "AI":
return false;
default:
console.log("Type not recognized");
}
}
}
module.exports = Player
Helper
class Helper{
constructor(){
this.gameType;
this.canvasLocator = document.querySelector("#gameCanvas");
this.canvasContext = this.canvasLocator.getContext("2d");
this.mouseXPos;
this.mouseYPos;
}
getMouseYPos(canvas, evt) {
var rect = canvas.getBoundingClientRect();
return (evt.clientY - rect.top);
}
playerInput(drawObj){
let c = this.canvasLocator;
let helper = this;
//let game = this;
//let mouseYPos;
//console.log(game);
c.addEventListener("mousemove", function(evt){
helper.mouseYPos = helper.getMouseYPos(c, evt);
}
, false);
//console.log(game.mouseYPos);
return helper.mouseYPos;
}
change(speed){
//Ball Function for reflection
if(speed > 8 || speed < -8){
return 2;
}
return (Math.abs(1/8 * speed) + 1);
}
randomIntNumber(min, max){
min = Math.ceil(min);
max = Math.floor(max);
return Math.floor(Math.random() * (max - min)) + min;
}
randomSpeed(){
if(this.randomIntNumber(0, 100) % 2 == 0){
return this.randomIntNumber(-7, -9);
}
else{
return this.randomIntNumber(7, 9);
}
}
randomNumber(min, max){
return (Math.random() * (max - min)) + min;
}
}
module.exports = Helper
Thank you for the help.
回答1:
For starters you asked how to import and export in ES6. Before I address that, it's important to note that ES6 module syntax is not the same thing as how Node.JS imports modules. Your examples are using Node.JS Common.js style module loading.
In ES6 you import modules like so...
import jquery from 'jquery';
or if you are loading something outside of your node_modules folder...
import myClass from './path/to/where/the/file/is';
The two examples I just provided are how you would load the entire file as a dependency.
Now if you just wanted to import a single function for use you could do that with ES6 as well.
test.js
const myFunction = () => { alert("hello world") };
export { myFunction }
Now you can import just myFunction like so...
import { myFunction } from './path/to/test.js';
All of this said, one thing you need to keep in mind is native browsers do not have the ability to import JavaScript modules yet. So to get around this problem, we need to use something like Webpack to provide the ability to import and export modules using ES6.
https://webpack.github.io/
来源：https://stackoverflow.com/questions/45764743/how-to-import-and-export-javascript-es6-classes