驗證陳述句難以閱讀

我需要了解這個陳述在 sintaxis/結構方面的含義：

defaultValue: (closureData != undefined) ? (closureColl[i]) ? [closureColl[i].collaboratorGroup   "--"   closureColl[i].collaboratorArea] : (areaFixedValue) ? [areaFixedValue] : (areaDefaultValue) ? [areaDefaultValue] : [] : []

我習慣跟隨sintaxis (condition) ? 'if true' : 'if false'

兩個“？”是什么意思？連續是什么意思？

uj5u.com熱心網友回復：

它們是嵌套的三元條件運算子。以這種方式嵌套三元組通常被認為是非常糟糕的做法，因為您遇到的原因是它們變得非常難以理解。您可以通過適當的縮進和括號使用來提高可讀性，但該行甚至沒有。

考慮一下你是否只有一個三元組：

const foo = isBarTrue ? trueValue : falseValue;

但是考慮一下 if trueValueare 本身，一個三元運算式，因為您可以任意嵌套運算式：

const foo = isBarTrue ? (isBazTrue ? truestValue : trueValue) : falseValue;

如果您洗掉括號，它會更加混亂到不可讀的程度：

const foo = isBarTrue ? isBazTrue ? truestValue : trueValue : falseValue;

一種有助于提高可讀性的約定是像這樣縮進三元組（有一些方便的 eslint 和更漂亮的插件會自動為您執行此操作，這很好）。基本上，每個?都會形成一個新的嵌套級別，由縮進線表示，而:符號“關閉”該級別的嵌套并將下一行移到最后一個 unmatched 的縮進級別?。起初有點令人困惑，但在這里它正在發揮作用：

const foo = isBarTrue
  ? isBazTrue
    ? truestValue
    : trueValue
  : falseValue;

您給定的運算式比我的示例更糟糕，看起來像四個嵌套的三元條件運算子（您可以計算?s 的數量），這太糟糕了。我很快會回來編輯這篇文章，看看我是否可以幫助你解開它。

編輯：為了解決這個問題，一種方法是重構并提取每個具有“a ? b : c”形式的單獨的三元組，而沒有像“x : y : z”這樣的奇怪雙精度數。嘗試拉出一旦拉出似乎就有意義的三元組 - 有時從運算式的每個“結束”開始并交替拉出單個運算式會很有幫助。此外，用上面的縮進樣式重寫它會很有幫助。

如果我們從這個開始：

const defaultValue = (closureData != undefined) ? (closureColl[i]) ? [closureColl[i].collaboratorGroup   "--"   closureColl[i].collaboratorArea] : (areaFixedValue) ? [areaFixedValue] : (areaDefaultValue) ? [areaDefaultValue] : [] : [];

嘗試用縮進樣式重寫它：

const defaultValue = (closureData != undefined)
  ? (closureColl[i])
    ? [closureColl[i].collaboratorGroup   "--"   closureColl[i].collaboratorArea]
    : (areaFixedValue)
      ? [areaFixedValue]
      : (areaDefaultValue)
        ? [areaDefaultValue]
        : []
  : [];

Now we can rewrite it as such, pulling out the last "full" ternary which kind of makes sense on its own, (areaDefaultValue) ? [areaDefaultValue] : []. Remember to replace the expression in the original ternary with the new equivalent value:

const conditionalAreaDefaultValue = (areaDefaultValue)
 ? [areaDefaultValue]
 : [];

const defaultValue = (closureData != undefined)
  ? (closureColl[i])
    ? [closureColl[i].collaboratorGroup   "--"   closureColl[i].collaboratorArea]
    : (areaFixedValue)
      ? [areaFixedValue]
      : conditionalAreaDefaultValue
  : [];

Then, pull out the first "full" ternary, which also sorta makes sense on its own, (closureColl[i]) ? [closureColl[i].collaboratorGroup "--" closureColl[i].collaboratorArea] : (areaFixedValue):

const conditionalAreaDefaultValue = (areaDefaultValue)
  ? [areaDefaultValue]
  : [];

const conditionalCollValue = (closureColl[i])
  ? [closureColl[i].collaboratorGroup   "--"   closureColl[i].collaboratorArea]
  : (areaFixedValue);

const defaultValue = (closureData != undefined)
  ? conditionalCollValue
    ? [areaFixedValue]
    : conditionalAreaDefaultValue
  : [];

From here the remaining nested ternaries are a bit easier to understand, and it looks like the middle part is doing a lot of work to determine the "final" value of this expression. Let's pull that part out, conditionalCollValue ? [areaFixedValue] : conditionalAreaDefaultValue:

const conditionalAreaDefaultValue = (areaDefaultValue)
  ? [areaDefaultValue]
  : [];

const conditionalCollValue = (closureColl[i])
  ? [closureColl[i].collaboratorGroup   "--"   closureColl[i].collaboratorArea]
  : (areaFixedValue);

const conditionalFinalValue = conditionalCollValue
  ? [areaFixedValue]
  : conditionalAreaDefaultValue;

const defaultValue = (closureData != undefined)
  ? conditionalFinalValue
  : [];

There is even more refactoring you could do here, especially with naming or converting things to if statements, but I will leave that to you. Hopefully this exercise sheds some light on what the heck is going on with that expression in the first place.

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