Question

基本上，我最近开始使用WebSockets，每当我从客户端->服务器发送创建新消息所需的JSON数据时，我都会首先使用提供的ID检查用户是否在聊天中从客户端返回的结果为false，即使此时正在检查的ID都相同

例如'abc'=='abc'将返回false

Checking: 5c2e13ee193dac483851677b === 5c2e13ee193dac483851677b -> false.

我尝试过控制台记录城市和city_id（由客户端提供）的类型，它们都是对象。我进行了.toString（）转换，以获取字符串，然后进行了.trim（）转换，即使不需要.toString（），因为它们已经是字符串了

public isInCity(city_id: string) {
    for(const planet of this.user.planets) {
        console.log(`Checking ${(planet as IPlanet)._id}`)
        for(const city of (planet as IPlanet).cities) {
            if(typeof city === 'string') {
                console.log(`\tChecking - s: ${city} === ${city_id} -> ${city === city_id}`)
                if(city == city_id) return true;
            } else {
                console.log(`\tChecking: ${city._id} === ${city_id} -> ${city._id === city_id}.`)
                if(city._id === city_id) return true;
            }
        }
    }
}

预期结果应该是：

Checking: 5c2e13ee193dac483851677b === 5c2e13ee193dac483851677b -> false.

应返回true

Checking 5c2df2a01260fa4aacb185f1
Checking 5c2df2a01260fa4aacb185f2
Checking 5c2df2a11260fa4aacb185f3
        Checking: 5c2df7b05eed7a168c402bbb === 5c2e13ee193dac483851677b -> 
false. 
        Checking: 5c2df7d2d97d783da00dddd1 === 5c2e13ee193dac483851677b -> 
false. 
        Checking: 5c2df7dee32f114614342f9f === 5c2e13ee193dac483851677b -> 
false. 
        Checking: 5c2df7ef08e3185224ac53db === 5c2e13ee193dac483851677b -> 
false. 
        Checking: 5c2df8986a91193170411e1d === 5c2e13ee193dac483851677b -> 
false. 
        Checking: 5c2e13ee193dac483851677b === 5c2e13ee193dac483851677b -> 
false.

不太确定是什么原因引起的，我花了很长时间试图弄清楚是什么，但我只是无法弄清楚

Answer 1

如果您知道两者的类型可能不同，但值可以相同也可以不相同，那么

use == instead of ===

因为 == 不会检查类型

比较两个相同的字符串时，返回false

1 个答案: