端口在飛鏢的js地圖

Question

我怎樣才能在dart中傳遞這個常量？

const CHANNEL_STATES = { 
    closed: "closed", 
    errored: "errored", 
    joined: "joined", 
    joining: "joining", 
    leaving: "leaving", 
} 

我需要它來調用前。 CHANNEL_STATES.closed 感謝

Answer 1

你可以做到這一點與類和常量靜態成員：

class CHANNEL_STATES { 
    static const String closed = "closed"; 
    static const String errored = "errored"; 
    static const String joined = "joined"; 
    static const String joining = "joining"; 
    static const String leaving = "leaving"; 
} 

Answer 2

我不知道你問的什麼，但在DART類似的地圖常數是：

const channelStates = const { 
    "closed": "closed", 
    "errored": "errored", 
    "joined": "joined", 
    "joining": "joining", 
    "leaving": "leaving", 
}; 

鏢地圖文字可以使用任何對象作爲重點，所以使用字符串作爲密鑰，您需要引用它。你不能像JavaScript中那樣使用一個沒有引號的標識符。