JavaScript switch 语句是线性的还是恒定的时间? [英] Is JavaScript switch statement linear or constant time?

问题描述

我的网站上有以下 JavaScript，以便在执行某些特定搜索时，答案被硬编码到特定页面:

I have the following JavaScript on my site so that when certain specific searches are performed, the answer is hardcoded to a specific page:

function redirect() {
    var input = document.getElementById('searchBox').value.toLowerCase();

    switch (input) {
      case 'rectangular':
        window.location.replace('http://www.Example.com/Rectangular/');
        break;
      case 'elephant':
        window.location.replace('http://www.Example.com/Elephants/');
        break;
      case 'coils':
        window.location.replace('http://www.Example.com/Parts/');
        break;
      default: // No keyword detected: submit the normal search form.
        return true;
        break;
    }
    return false; // Don't let the form submit
}

我想知道 JavaScript 中的搜索语句是否与 case 语句的数量或常数时间成线性关系?如果是线性的，是否有更好的方法来编写此代码，无论我编写多少特殊情况，它都是恒定时间?

I'm wondering whether the search statement in JavaScript is linear on the number of case statements or constant time? If linear, is there a better way to write this code so it is constant time regardless of the number of special cases I code?

推荐答案

这里相当于 Bergi 在 ES5 中的回答.与您现在使用的相比，它会更快且更容易修改.

Here's the equivalent of Bergi's answer in ES5. It'll be fast and also a lot easier to modify compared to what you're using now.

var _redirectlist = {
  'rectangular': 'http://www.Example.com/Rectangular/',
  'elephant': 'http://www.Example.com/Elephants/',
  'coils': 'http://www.Example.com/Parts/'
};

function redirect() {
  var input = document.getElementById('searchBox').value.toLowerCase();

  // Redirect if we have the input in our list
  if (_redirectlist.hasOwnProperty(input)) {
    window.location.replace(_redirectlist[input]);
    return false;
  }

  return true;
}

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