如何检查Javascript中是否只有一个值不为空? [英] How to check if only one value is not null in Javascript?

问题描述

假设我在 cshtml 中有 3 个文本框.我在 Javascript 中尝试做的是以下内容:

Let's say I have 3 textboxes in cshtml. What I am trying to do in Javascript is the following:

检查这 3 个值中的任何一个和 ONLY THEM 是否不为空.

Check if ANY OF those 3 values and ONLY THEM is not null.

我能想到的唯一方法是手动进行:

The only way I can think of is doing it manually:

if ((val1 & !val2 & !val3) || (!val1 & val2 & !val3) || (!val1 & !val2 & val3))

如果文本框数量少也没关系，但如果这样的数字增长到 10+，可能会变得很麻烦.

It is okay if it is a small number of textboxes, but if such number grows to 10+, it might become a hassle.

无论我们处理多少个文本框，有没有什么有效的方法可以在 Javascript 中实现这种逻辑?

推荐答案

你可以使用 .reduce:

var nonEmpty = [val1, val2, val3].reduce(((c, v) => c += (v !== "")), 0);
if (nonEmpty === 1) {
  // exactly one is not empty
}

任何其他计算非空输入并检查计数是否等于 1 的方法当然也可以.

Any other way of counting the non-empty inputs and checking that the count is equal to 1 would work too of course.

.reduce() 代码的作用是使用箭头函数"，当值不是空字符串时，它会增加计数器 (c).(如果你想检查 null，你可以这样做，而不是当然.)你也可以使用一个普通的老式函数:

What that .reduce() code does is use an "arrow function" that increments a counter (c) when a value is not the empty string. (If you want to check for null, you can do that instead of course.) You could use a plain old-fashioned function too:

var nonEmpty = [val1, val2, val3].reduce(function(c, v) {
  return c += (v !== "");
}, 0);

.reduce() 函数传递了 2 个参数:回调函数和 c 的初始值(在本例中为零).返回值将是最后一次调用回调返回的 c 的 final 值.

The .reduce() function is passed 2 parameters: that callback function, and the initial value of c (zero in this case). The return value will be the final value of c returned by the last call to the callback.

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