Javascript - if 和 else 语句都执行

Question

我的代码正在尝试组装一个给定大小的可视棋盘，然后将其输出到 console.log 。基本上，它:

• 循环面板中的所有行
• 循环遍历该行中的所有列
• 如果列位于偶数行中，则会放置一个空格
• 如果列位置在奇数行中为偶数，则会放置一个黑色空格。

我的代码:

var sz = Number(prompt("What size chessboard?"))
console.log("Board of size " + sz + " selected.") 
var row = 0
var rowType = "even"
var col = 0
var bd = ""
var whiteSpace = "[]"
var blackSpace = "()"

for (row; row <= sz; row++) {
  if (row % 2 == 0) {rowType = "even";}  // For even rows, all even column places are white
  else {rowType = "odd";}  // and for odd rows, all even column places are black
  for (col = 0; col <= sz; col++) {
    if (col % 2 == 0) {
      if (rowType == "even") {bd += whiteSpace;}
      if (rowType == "odd") {bd += blackSpace;}
      else {console.log("Something went terribly wrong.")}  // This should never happen... right?
    }
    else {
      if (rowType == "even") {bd += blackSpace;}
      if (rowType == "odd") {bd += whiteSpace;}
      else {console.log("Something went horribly wrong.")}  // Not this one either?
    }
  }
  bd += "\n"
}
console.log(bd)

出于某种原因，我输入的额外代码只是为了捕获 if 的情况，不知何故，rowType似乎总是不执行“偶数”或“奇数”，将“发生了可怕/可怕的错误”放在 console.log 中即使代码运行良好并且电路板实际上已正确生成。

我的问题不在于如何删除这些行，显然我可以删除 else block ，但我很好奇我的错误在哪里，导致它首先运行。

有什么想法吗？

Answer 1

当你拥有它时，你正在做:

if (rowType == "even") {bd += whiteSpace;}
if (rowType == "odd") {bd += blackSpace;}
else {console.log("Something went terribly wrong.")} // <- will execute if
                                                     //    not 'odd'

应该是:

if (rowType == "even") {bd += whiteSpace;}
else if (rowType == "odd") {bd += blackSpace;}
else {console.log("Something went terribly wrong.")} // <- will execute if
                                                     //    not 'even' or 'odd'