Javascript数组中的魔术逗号
我正在编写一个数独验证器作为练习问题。我在一行中导入了一个81位的线路板，由一个空格分隔为一个字符串。当我在第4行打印字符串时，输入中的数字之间没有逗号分隔。在第14行，我使用split方法将它拆分为一个数组，该数组的长度应该是81个索引。当我通过打印20行的数组来测试它时，数字之间的索引已经由逗号填充。我不知道这些神奇的逗号是从哪里来的，它一定是split方法的结果，因为我的输入不包含任何逗号。有人能解释一下发生了什么吗？下面是JS脚本：
function import1() {
var board = prompt("Please enter a board");
if (board != null) {
document.getElementById("demo").innerHTML = "board entered: " + board + "\n";
}
else {
document.getElementById("demo").innerHTML = "Invalid entry\n";
}
parseMe(board);
}
function parseMe(board) {
var boardArray = String(board.split(" "));
var toPrint = "";
for (var j = 0; j < boardArray.length; j++) {
toPrint += boardArray[j];
}
document.getElementById("test").innerHTML = "test" + toPrint;
var board2D = [
["0", "0", "0", "0", "0", "0", "0", "0", "0"],
["0", "0", "0", "0", "0", "0", "0", "0", "0"],
["0", "0", "0", "0", "0", "0", "0", "0", "0"],
["0", "0", "0", "0", "0", "0", "0", "0", "0"],
["0", "0", "0", "0", "0", "0", "0", "0", "0"],
["0", "0", "0", "0", "0", "0", "0", "0", "0"],
["0", "0", "0", "0", "0", "0", "0", "0", "0"],
["0", "0", "0", "0", "0", "0", "0", "0", "0"],
["0", "0", "0", "0", "0", "0", "0", "0", "0"]
];
var counter = 0;
for (var i = 0; i < board2D.length; i++) {
for (var j = 0; j < board2D.length; j++) {
board2D[i][j] = boardArray[counter];
counter++;
}
}
if (counter != 81) {
document.getElementById("error").innerHTML = "Invalid entry, should be 81 total digits\n";
}
printBoard(board2D);
}
function printBoard(board) {
var toPrint = "";
for (var i = 0; i < board.length; i++) {
for (var j = 0; j < board.length; j++) {
toPrint += board[i][j] + " ";
}
toPrint += "\n";
}
document.getElementById("printBoard").innerHTML = toPrint;
}如果有人想看我写的网页，我可以提供给你，但我不认为这有什么关系。
下面是输出的样子：
进入董事会:5 3 4 6 7 8 9 1 2 7 7 2 1 9 5 3 4 8 1 9 8 3 4 2 5 6 7 8 5 9 7 6 1 1 2 3 4 2 6 8 5 3 7 9 1 1 1 3 3 2 4 8 5 6 6 6 1 5 3 7 7 2 8 2 8 7 4 1 9 6 3 5 3 4 5 2 8 6 1 7 9
test5,3,4,6,7,8,9,1,2,6,7,2,1,9,5,3,4,8,1,9,8,3,4,2,5,6,7,8,5,9,7,6,1,4,2,3,4,2,6,8,5,3,7,9,1,7,1,3,9,2,4,8,5,6,9,6,1,5,3,7,2,8,4,2,8,7,4,1,9,6,3,5,3,4,5,2,8,6,1,7,9
回答 2
Stack Overflow用户
发布于 2018-08-10 04:55:41
当从board.split(" ") (数组)转换为字符串时，将插入逗号。请参阅文档here)和下面的示例：
var test = ['1', '2', '3'];
console.log(test[0], test[1]);
var testAsString = String(test);
console.log(testAsString[0], testAsString[1]);
您不需要将其从数组中转换回来，只需正常访问元素即可。
function import1() {
var board = prompt("Please enter a board");
if (board != null) {
document.getElementById("demo").innerHTML = "board entered: " + board + "\n";
}
else {
document.getElementById("demo").innerHTML = "Invalid entry\n";
}
parseMe(board);
}
function parseMe(board) {
var boardArray = board.split(" ");
var toPrint = "";
for (var j = 0; j < boardArray.length; j++) {
toPrint += boardArray[j];
}
document.getElementById("test").innerHTML = "test" + toPrint;
var board2D = [
["0", "0", "0", "0", "0", "0", "0", "0", "0"],
["0", "0", "0", "0", "0", "0", "0", "0", "0"],
["0", "0", "0", "0", "0", "0", "0", "0", "0"],
["0", "0", "0", "0", "0", "0", "0", "0", "0"],
["0", "0", "0", "0", "0", "0", "0", "0", "0"],
["0", "0", "0", "0", "0", "0", "0", "0", "0"],
["0", "0", "0", "0", "0", "0", "0", "0", "0"],
["0", "0", "0", "0", "0", "0", "0", "0", "0"],
["0", "0", "0", "0", "0", "0", "0", "0", "0"]
];
var counter = 0;
for (var i = 0; i < board2D.length; i++) {
for (var j = 0; j < board2D.length; j++) {
board2D[i][j] = boardArray[counter];
counter++;
}
}
if (counter != 81) {
document.getElementById("error").innerHTML = "Invalid entry, should be 81 total digits\n";
}
printBoard(board2D);
}
function printBoard(board) {
var toPrint = "";
for (var i = 0; i < board.length; i++) {
for (var j = 0; j < board.length; j++) {
toPrint += board[i][j] + " ";
}
toPrint += "\n";
}
document.getElementById("printBoard").innerHTML = toPrint;
}
import1();<div id="demo"></div>
<div id="test"></div>
<div id="printBoard"></div>
<div id="error"></div>
Stack Overflow用户
发布于 2018-08-10 04:58:03
执行此操作时：
String(board.split(" "));
for (var j = 0; j < boardArray.length; j++) {
toPrint += boardArray[j];
}
document.getElementById("test").innerHTML = "test" + toPrint;您需要记住，String(board.split(" "));正在将数组转换为字符串，这将导致在表示中包含一些逗号。
所以当你迭代的时候，你会遍历字符串的字符，然后用逗号复制它。
您不需要将其转换为字符串！
https://stackoverflow.com/questions/51775533
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