Javascript:为什么警报说未定义而不是字母"k"? [英] Javascript: why is the alert saying undefined and not the letter "k"
问题描述
我可以让我的数组工作并完美地显示为2d数组，但第二个尝试添加另一个从未显示过的元素，该元素永远不会保持未定义状态.我尝试了许多不同的方法，在此版本中，我尝试复制添加2d元素的方式.
I can get my array to work and display perfectly as a 2d array but the second I attempt to add another element it never shows it always stays undefined. I tried many different methods, in this version I attempted to duplicate the way that I add the 2d elements.
最终，我想将数据保存到数组中，以使正确显示的墙#"具有进一步的数据，表明实心"，然后在移动"@"之前可以进行测试
Ultimately I want to save data to the array to make the walls "#" that are displaying correctly to have further data stating "solid" and then I would be able to test for that before moving the "@"
我实际上有一个工作版本，但是使用第二个数组，如果我添加更多数据，将会非常麻烦.
I actually have a working version of this but using a second array which would get very cumbersome if I add further data.
现在也很奇怪，整个地图没有被字母k覆盖
Also as it is right now I am surprised the entire map is not getting overwritten with the letter k
function gameloop(){
var mainArray = [];
var mapSizeX = 32;
var mapSizeY = 128;
var arrayDepth = 10;
var idPos = {x:0, y:0};
function initMap(mainArray, mapSizeX, mapSizeY){
for (var i = 0; i < mapSizeX; i++) {
mainArray.push([0])
for (var j = 0; j < mapSizeY; j++) {
mainArray[i][j] = ".";
if(j == 0){mainArray[i][j] = "#";}
if(j == mapSizeY-1){mainArray[i][j] = "#";}
if(i == 0){mainArray[i][j] = "#";}
if(i == mapSizeX-1){mainArray[i][j] = "#";}
for (var k = 0; k < arrayDepth; k++) {
mainArray[i][j][k] = "k";
}
}
}
}
function nl(){GameScreen.innerText += "\n";}
function render() {GameScreen.innerText = mainArray.map(arr => arr.join("")).join("\n");
nl(); nl();}
function reposition(xChange,yChange,strA){
//mainArray[idPos.x][idPos.y] = ".";
//idPos.x = idPos.x + xChange;
//idPos.y = idPos.y + yChange;
//mainArray[idPos.x][idPos.y] = "@";
if(mainArray[idPos.x+xChange][idPos.y+yChange][1] === "Solid"){GameLog.innerText ="You can not travel in that direction"}
else{
mainArray[idPos.x][idPos.y] = ".";
idPos.x = idPos.x + xChange;
idPos.y = idPos.y + yChange;
mainArray[idPos.x][idPos.y] = "@";
GameLog.innerText = "You take a step to the " + strA
alert(mainArray[0][0][1]);
}
render();
}
//Startup
initMap(mainArray, mapSizeX, mapSizeY);
idPos.x = mapSizeX/2; idPos.y = mapSizeY/2;
mainArray[idPos.x][idPos.y] = "@";
//First Render
render();
document.addEventListener('keydown', function(event) {
if(event.keyCode === 38 ){reposition(-1,0,"North");}
if(event.keyCode === 40 ){reposition(1,0,"South");}
if(event.keyCode === 37 ){reposition(0,-1,"West");}
if(event.keyCode === 39 ){reposition(0,1,"East");}
//alert(event.keyCode);
});
}
gameloop();<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Hello</title>
</head>
<body>
<br>
<p style="color:#7d7d7d;font-family:Lucida Console;">Dungeon Valley.<br>
<font style="color:#ABABAB;font-family:Lucida Console;font-size:0.5em";>
Taming the Borderlands.<br>
v0.005 By heromedel. </P></font>
<P>
<section id="GameScreen" style="color:#000000;font-family:Lucida Console;"></section>
<P>
<section id="GameLog" style="color:#000000;font-family:Lucida Console;">Arrow Keys to move.<br></section>
<script src="main.js"></script>
</body>
</html>推荐答案
如果我了解您要执行的操作，这是错误的:
If I'm understanding what you're trying to do, this is wrong:
for (var k = 0; k < arrayDepth; k++) {
mainArray[i][j][k] = "k";
}
mainArray 应该是二维的字符串数组，对吗?那么，为什么要使用 var k 向其中添加第3维?除非您尝试附加到字符串?在Javascript中，您使用 + 附加字符串，而不使用 [] .
mainArray is supposed to be a 2d array of strings, right? So why are you using var k to add a 3rd dimension to it? Unless you're trying to append to the string? In Javascript you append to strings with +, not with [].
顺便说一句，这也是错误的:
By the way, this is also wrong:
mainArray.push([0])
您要推送一个空数组 [] ，而不是其中包含0的数组 [0] .
You want to push an empty array [], not an array with a 0 in it [0].
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