TypeError模塊中的語句不讓函數無第二個參數

Question

我想爲String對象添加一個函數，它搜索所有字符串並返回我們想要查找的字的索引。當我不使用startIndex參數時，它不應該拋出第二個錯誤，因爲這個語句typeof startIndex !== "undefined"讓這個函數在沒有startIndex的情況下工作。請糾正我，並感謝您的幫助。

String.prototype.allIndexOf = allIndexOfFunction; 

function allIndexOfFunction(string, startIndex) { 
    startIndex = startIndex || 0 
    var indexArr = []; 
    var sIndex = 0; 
    var baseString = this.concat(); 
    if (typeof string === "string" && typeof startIndex === "number" && startIndex >= 0) { 
     while(sIndex !== -1){ 
      sIndex = baseString.indexOf(string, startIndex); 
      if(sIndex !== -1){ 
       indexArr.push(sIndex); 
       startIndex = startIndex + sIndex +1; 
      } 
     } 
    } 
    try { 
     if (typeof string !== "string") { 
      throw "First parameter must be a string type"; 
     } 
     else if (typeof startIndex !== "number" || typeof startIndex !== "undefined") { 
      throw "Second parameter must be a number type"; 
     } 
     else if (startIndex <= 0) { 
      throw "Second parameter must be equal or bigger than 0"; 
     } 
    } catch(err) { 
     console.log(err); 
    } 

    return indexArr; 
} 
//TEST 
var a = "Lorem ipsum dolor sit Buzz, consectetur Buzz elit. Quod vero voluptatibus Buzz error deserunt libero, Buzz incidunt Buzz facere! A!"; 
var test = a.allIndexOf("Buzz"); 
console.log("Searching indexes of \"Buzz\" word in string -> " + a); 
console.log(test); 

Answer 1

簡單的問題。你的邏輯是不完全正確 - 你需要的，而不是OR：

你一個行更改爲：

else if (typeof startIndex !== "number" && typeof startIndex !== "undefined") {

而且，由於你默認爲0，如果沒有定義的startIndex，那麼你就不要根本不需要第二個條件測試。

你可以看到它運行如下預期：

String.prototype.allIndexOf = allIndexOfFunction; 
 

 
function allIndexOfFunction(string, startIndex) { 
 
    startIndex = startIndex || 0 
 
    var indexArr = []; 
 
    var sIndex = 0; 
 
    var baseString = this.concat(); 
 
    if (typeof string === "string" && typeof startIndex === "number" && startIndex >= 0) { 
 
    while(sIndex !== -1){ 
 
     sIndex = baseString.indexOf(string, startIndex); 
 
     if(sIndex !== -1){ 
 
     indexArr.push(sIndex); 
 
     startIndex = startIndex + sIndex +1; 
 
     } 
 
    } 
 
    } 
 
    try { 
 
    if (typeof string !== "string") { 
 
     throw "First parameter must be a string type"; 
 
    } 
 
    else if (typeof startIndex !== "number") { 
 
     throw "Second parameter must be a number type"; 
 
    } 
 
    else if (startIndex <= 0) { 
 
     throw "Second parameter must be equal or bigger than 0"; 
 
    } 
 
    } catch(err) { 
 
    console.log(err); 
 
    } 
 

 
    return indexArr; 
 
} 
 
//TEST 
 
var a = "Lorem ipsum dolor sit Buzz, consectetur Buzz elit. Quod vero voluptatibus Buzz error deserunt libero, Buzz incidunt Buzz facere! A!"; 
 
var test = a.allIndexOf("Buzz"); 
 
console.log("Searching indexes of \"Buzz\" word in string -> " + a); 
 
console.log(test);