JavaScript问号&双管 [英] Javascript Question Mark & Double Pipes

问题描述

我是javascript新手，到目前为止，据我了解:

I am new to javascript and so far it is my understanding that:

?& :用于如果为true，请执行此操作，如果为false，请执行此操作"

? & : is used for "if true, do this, if false do this"

但是，我在||上遇到了更多麻烦.从我的浏览看来，如果第一个是正确的，则执行此操作，否则执行此操作"

However, I am having a little more trouble with ||. From my browsing it seems something like "if the first one is true do that, otherwise do this"

我正在尝试找出以下代码-在这种情况下有关它们的含义的任何建议吗?:

I am trying to figure out the following code - any suggestions on what they mean together in this context?:

function isSubset(series, description){
    var subset = true;
    var exactMatch = true;
    demoCodes = ['age', 'edu', 'race', 'sex'];
    for (var i = 0; i < demoCodes.length; i++){
        var demoCode = demoCodes[i];
        subset = (subset) ? (description[demoCode] == 0 || description[demoCode] == series[demoCode]) : false;
        exactMatch = (exactMatch) ? description[demoCode] == series[demoCode] : false;
    }
    return {subset: subset, exactMatch: exactMatch};
}

谢谢！干杯

推荐答案

||表示或".首先评估||的左侧.如果解析为true，则表达式解析为true.另一方面，如果||运算符的左侧解析为false，则将对右侧进行求值并返回.

|| means "or". The left side of the || is evaluated first. If it resolves to true, then the expression resolves to true. If, on the other hand, the left side of the || operator resolves to false, then the right side will be evaluated and returned.

示例1:

1 == 1 || 1 == 0

由于||的左侧，因此将评估为true.运算符为真.

Will evaluate to true, since the left side of the || operator is true.

示例2:

1 == 2 || 1 == 1

左侧解析为false，因此对右侧进行求值并返回.在这种情况下，1 == 1，因此整个表达式(1 == 2 || 1 == 1)解析为true.

The left side resolves to false, so the right side is evaluated and returned. In this case, 1==1 so the whole expression (1 == 2 || 1 == 1) resolves to true.

示例3:

1 == 2 || 1 == 3

左侧解析为false，因此对右侧进行求值并返回.在这种情况下，1不等于3，因此整个表达式(1 == 2 || 1 == 3)解析为false.

The left side resolves to false, so the right side is evaluated and returned. In this case, 1 does not equal 3, so the whole expression (1 == 2 || 1 == 3) resolves to false.

为了简单起见，如果任一表达式由||保持在一起"运算符为true，则表达式将返回true.否则，它将返回false.

To put it more simply, if either of the expressions "held together" by the || operator are true, then the expression will return true. Otherwise, it will return false.

这篇关于JavaScript问号&双管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IT屋！