從函數傳遞變量作爲參數

Question

我想傳遞一個數組，我已經保存爲var。我在父函數中聲明var，並在父函數中添加arr作爲參數。然後，我將arr作爲回調調用中的參數。 控制檯告訴我linksA是未定義的。

var supportLists = function(selector, arr) { 
    var parentList = document.getElementById(selector); 
    var theList = parentList.querySelectorAll("a"); 

    var linksA = [ 
     "http://www.example.com", 
     "http://www.example.com/path2", 
     "1", 
     "2", 
     "4", 
     "3", 
     "5", 
     "6", 
     "7" 
    ]; 

    var linksB = [ 
     "1", 
     "2", 
     "3" 
    ]; 

    var linksC = [ 
     "1", 
     "2", 
     "3", 
     "4", 
     "5", 
     "6", 
     "7", 
     "8", 
     "9", 
     "10", 
     "11", 
     "12" 
    ]; 

    var linksD = [ 
     "1", 
     "2" 
    ]; 

    var linksE = [ 
     "1", 
     "2", 
     "3" 
    ]; 

    var linksF = [ 
     "1", 
     "2", 
     "3", 
     "4", 
     "5", 
     "6" 
    ]; 

    var linksG = [ 
     "1", 
     "2", 
     "3" 
    ]; 

    var linksH = [ 
     "1", 
     "2", 
     "3", 
     "4" 
    ]; 

    var linksI = [ 
     "1" 
    ]; 

    var linksJ = [ 
     "1", 
     "2", 
     "3", 
     "4", 
     "5" 
    ]; 

    function processLi(listItems, links) { 

     for (var i = 0; i < links.length; i++) { 

      listItems.forEach(function(item, index) { 
       item.href = links[index]; 
       item.target = "_blank"; 

      }); 

     } 
    } 

    processLi(theList, arr); 
}; 

supportLists("support-list", linksA); 
supportLists("support-list-b", linksB); 
supportLists("support-list-c", linksC); 
supportLists("support-list-d", linksD); 
supportLists("support-list-e", linksE); 
supportLists("support-list-f", linksF); 
supportLists("support-list-g", linksG); 
supportLists("support-list-h", linksH); 
supportLists("support-list-i", linksI); 
supportLists("support-list-j", linksJ); 

Answer 1

如果你想用它在你想使用它或將它傳遞（給一個函數）的範圍，這意味着它在該範圍或將被宣佈爲獲得一個變量一個父範圍。

由於您將數組傳遞給supportLists函數，因此您必須在該函數之外聲明它們。

如果移動功能以外的所有數組聲明您的代碼會是這個樣子（我增加了一些註解，以顯示其中一個範圍開始，在哪裏結束）

// This is the 'parent' scope (probably the global/window scope in your case) 

var linksA = [ 
    "http://www.example.com", 
    // ... 
]; 

// ... 

var linksJ = [ 
    "1", 
    "2", 
    "3", 
    "4", 
    "5" 
]; 

var supportLists = function(selector, arr) { 
    // Here begins the 'supportLists' function scope 
    // The 'supportLists' function has access to this scope and the 'parent' scope 
    var parentList = document.getElementById(selector); 
    var theList = parentList.querySelectorAll("a"); 

    function processLi(listItems, links) { 
     // Here begins the 'processLi' function scope 
     // The 'processLi' function has access to this scope, the 'supportLists' scope and the 'parent' scope 

     for (var i = 0; i < links.length; i++) { 

      listItems.forEach(function(item, index) { 
       // Here begins the 'function(item, index)' function scope 
       // The 'function(item, index)' function has access to this scope, the 'processLi' scope, the 'supportLists' scope and the 'parent' scope 

       item.href = links[index]; 
       item.target = "_blank"; 
      });// Here ends 'function(item, index)' function scope 
      // Back in the 'processLi' function scope 
     } 
    } // Here ends the 'processLi' function scope 
    // Back in the 'supportLists' function scope 

    processLi(theList, arr); 
}; // Here ends the 'supportLists' function scope 
// Back in the 'parent' scope 

supportLists("support-list", linksA); 
supportLists("support-list-b", linksB); 
supportLists("support-list-c", linksC); 
supportLists("support-list-d", linksD); 
supportLists("support-list-e", linksE); 
supportLists("support-list-f", linksF); 
supportLists("support-list-g", linksG); 
supportLists("support-list-h", linksH); 
supportLists("support-list-i", linksI); 
supportLists("support-list-j", linksJ); 

Answer 2

目前，您的變量在本地範圍內定義，因此它們在supportLists函數外部不可見。

解決方案：

定義函數外部的變量。例如，

var linksB = ["1", "2", "3"]; 
var supportLists = function(selector, arr) { //YOUR CODE }