为什么 Javascript `if...else if` 不会以 `else` 结尾? [英] Why would Javascript `if...else if` not end with an `else`?

问题描述

这是我正在使用的教程中的一段 JavaScript 代码.我不明白为什么它不以最后的 else 子句结尾；我认为这是一个规则.

Here is a snippet of JavaScript code from a tutorial I was working with. I don’t understand why it doesn’t end with a final else clause; I thought that was a rule.

var curScene = 0;

function changeScene(decision) {
  var message = "";

  if(curScene == 1) {
    message = " welcome";
  } else if (curScene == 2) {
    message = " this is scene two";
  } else if (curScene == 3) {
    message = " this is scene three";
  }

  document.getElementById("sceneimg").src = "scene" + curScene + ".png";

  if(message != ""){
    alert(message);
  }
}

推荐答案

我认为它总是应该以else"结尾?

I thought it was always supposed to end with an "else"?

else 块是可选的.你可以有 if 而没有 else.

The else block is optional. You can have if without else.

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