javascript - 使用短路逻辑运算符测试空对象

Question

我正在通读 Mozilla Developer Network's page on Javascript ，并被我看到的一条线弄糊涂了。这是有问题的描述和行:

The && and || operators use short-circuit logic, which means whether they will execute their second operand is dependent on the first. This is useful for checking for null objects before accessing their attributes:

var name = o && o.getName();

我在这里的困惑是，大概该片段的目的是执行:

var name;
if (o){
     name = o.getname();
}  

但是，看起来这里发生的是 name 被分配了一个 bool 值，并且该 bool 值是“o 存在并且它的名称不为空”。换句话说，对我来说它看起来像:

var name = false;
if (o && o.getname()){
    name = true;
}

谢谢!

Answer 1

这个答案是Felix Kling的评论我希望他将其发布为自己的答案以获得奖励的声誉

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看看Logical Operators ，在最顶端:

"Logical operators are typically used with Boolean (logical) values; when they are, they return a Boolean value. However, the && and || operators actually return the value of one of the specified operands, so if these operators are used with non-Boolean values, they may return a non-Boolean value."