JavaScript替代方案

本文介绍了JavaScript替代方案的处理方法，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小编来一起学习吧！ 问题描述

这段代码代表什么？我知道它是某种如果替代语法......

What does this bit of code represent? I know it's some kind of if alternative syntax...

pattern.Gotoccurance.score != null ? pattern.Gotoccurance.score : '0'

更新：

这种编码有什么需要？这是效率更高还是效率相同的缩短版本？

What's the need for this sort of coding? Is this more efficient or just a shortened version with the same efficiency?

推荐答案

这是条件运算符，它相当于这样：

It is the conditional operator, it is equivalent to something like this:

if (pattern.Gotoccurance.score != null) { pattern.Gotoccurance.score; } else { '0'; }

但我认为你发布的代码中缺少一个赋值语句，比如这个：

But I think that an assignment statement is missing in the code you posted, like this:

var score = pattern.Gotoccurance.score !=null ? pattern.Gotoccurance.score : '0';

如果<分配得分变量code> pattern.Gotoccurance.score 不为空：

The score variable will be assigned if pattern.Gotoccurance.score is not null:

var score; if (pattern.Gotoccurance.score != null) { score = pattern.Gotoccurance.score; } else { score = '0'; }

在JavaScript中执行此类默认值分配的常见模式是使用逻辑OR运算符（ || ）：

A common pattern to do this kind of 'default value' assignments in JavaScript is to use the logical OR operator (||) :

var score = pattern.Gotoccurance.score || '0';

pattern.Gotoccurance.score 的值仅当该值不是 falsy 时才会被分配到得分变量（假值为 false ， null ， undefined ， 0 ，零 - 长度字符串或 NaN ）。

The value of pattern.Gotoccurance.score will be assigned to the score variable only if that value is not falsy (falsy values are false, null, undefined, 0, zero-length string or NaN).

否则，如果它是假的'0'将被分配。

Otherwise, if it's falsy '0' will be assigned.

更新：性能相当，你应该专注于可读性，我尝试使用表达式上的三元运算符非常简单，你也可以改进格式，将它分成两行以使其更具可读性：

Update: The performance will be equivalent, you should focus on readability, I try to use the ternary operator on expressions that are very simple, and you can also improve the formatting, splitting it up in two lines to make it more readable:

var status = (age >= 18) ? "adult" : "minor";

相关问题：

• To Ternary还是Not to Ternary？

• To Ternary or Not To Ternary?