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        是否可以在 switch 语句中使用 .contains() ?

        Is it possible to use .contains() in a switch statement?(是否可以在 switch 语句中使用 .contains() ?)

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                  本文介绍了是否可以在 switch 语句中使用 .contains() ?的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着跟版网的小编来一起学习吧!

                  问题描述

                  这只是我正在尝试做的一个简单示例:

                  This is just a simple example of what I'm trying to do:

                  switch (window.location.href.contains('')) {
                      case "google":
                          searchWithGoogle();
                          break;
                      case "yahoo":
                          searchWithYahoo();
                          break;
                      default:
                          console.log("no search engine found");
                  }
                  

                  如果不可能/不可行,那么更好的选择是什么?

                  If it's not possible/feasible what would be a better alternative?

                  解决方案:

                  在阅读了一些回复后,我发现以下是一个简单的解决方案.

                  After reading some of the responses I found the following to be a simple solution.

                  function winLocation(term) {
                      return window.location.href.contains(term);
                  }
                  switch (true) {
                      case winLocation("google"):
                          searchWithGoogle();
                          break;
                      case winLocation("yahoo"):
                          searchWithYahoo();
                          break;
                      default:
                          console.log("no search engine found");
                  }
                  

                  推荐答案

                  是的",但它不会像你期望的那样.

                  "Yes", but it won't do what you expect.

                  用于切换的表达式被评估一次 - 在这种情况下,contains 评估结果为真/假(例如 switch(true)switch(false)), 不是一个 case 中可以匹配的字符串.

                  The expression used for the switch is evaluated once - in this case contains evaluates to true/false as the result (e.g. switch(true) or switch(false)) , not a string that can be matched in a case.

                  因此,上述方法行不通.除非此模式更大/可扩展,否则只需使用简单的 if/else-if 语句.

                  As such, the above approach won't work. Unless this pattern is much larger/extensible, just use simple if/else-if statements.

                  var loc = ..
                  if (loc.contains("google")) {
                    ..
                  } else if (loc.contains("yahoo")) {
                    ..
                  } else {
                    ..
                  }
                  

                  但是,请考虑是否存在返回google"或yahoo"等的classify 函数,可能使用上述条件.然后它可以这样使用,但在这种情况下可能会过大.

                  However, consider if there was a classify function that returned "google" or "yahoo", etc, perhaps using conditionals as above. Then it could be used as so, but is likely overkill in this case.

                  switch (classify(loc)) {
                     case "google": ..
                     case "yahoo": ..
                     ..
                  }
                  

                  <小时>

                  虽然上面讨论了 JavaScript 中的此类问题,但 Ruby 和 Scala(可能还有其他)提供了处理一些更高级开关"使用的机制.


                  While the above discusses such in JavaScript, Ruby and Scala (and likely others) provide mechanisms to handle some more "advanced switch" usage.

                  这篇关于是否可以在 switch 语句中使用 .contains() ?的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持跟版网!

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