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Question

代碼中的枚舉接受參數值，參數gender是enum type，該值必須是["male","female"]之一，但我想用它只是這樣judgeGender("male")，我該怎麼做呢？

function judgeGender(gender){ 
    //...... 
} 

Answer 1

你可以做的是接受一個String和check that it exists in the Enum，像這樣：

enum Gender {Male, Female}; 

function validGender(c: String) { 
    if(enumHasValue(Gender, c)) { 
     document.write(`valid gender: ${c}`); 
    } else { 
     document.write(`invalid gender: ${c}`); 
    } 
} 

function enumHasValue(e, v) { 
    for (var enumMember in e) { 
     if (enumMember === v) { 
      return true; 
     } 
    } 
    return false; 
} 

validGender("Female"); // => "valid gender: Female" 
document.write("<br/>"); 
validGender("Alien"); // => "invalid gender: Alien" 

試試這個例子列於TypeScript Playground（複製和粘貼，然後按運行）。

Answer 2

您可以創建一個函數來解析gender參數，就像這樣：

function parseGender(value : Gender | number | string) { 
    var gender; 
    if (value === Number(value)) { 
    gender = <Gender>value; 
    } 
    else if (value === String(value)) { 
    if (<string>value in Gender) { 
     gender = Gender[value]; 
    } 
    } 

    if (!gender) throw new TypeError("The parameter gender is incorrect"); 
    return gender; 
} 

然後你就可以使用它自己的函數中：

function judgeGender(gender : Gender | number | string) { 
    var g = parseGender(gender); 

    // do whatever you want with g 
} 

Answer 3

您可以指定哪些值你能功能接收。

type Male = "male"; 
type Female = "female"; 

enum Gender { 
    Male = Male, 
    Female = Female 
} 

function judgeGender(gender: Gender | Male | Female) { 
    //...... 
} 

judgeGender(Gender.Male); 
judgeGender("male");