Question

我厌倦了有限的javascript数组函数，并希望编写一些我自己的便捷原型函数来执行Set Theory函数。

以下是我迄今为止的代码

<script type="text/javascript">

Array.prototype.contains = function(obj) {
    var i = this.length;
    while (i--) {
        if (this[i] === obj) {
            return true;
        }
    }
    return false;
}

Array.prototype.getIndices = function(obj){
    var indices = new Array();
    var i = this.length;
    while (i--) {
        if(this[i] === obj){
            indices.push(i);
        }
    }
    return indices;
}

Array.prototype.Union = function(arr){
    //combines two arrays together to return a single array containing all elements (once)
    //{1,2,3,4,5}.Union({3,4,5,6,7})
    //returns: {1,2,3,4,5,6,7}
        var primArray = this;
        var secondArray = arr;
    var i = primArray.length;
    while(i--){
        if(secondArray.contains(primArray[i])){
            primArray.splice(i, 1);
        }
    }
    var returnArr = primArray.concat(secondArray);
    return returnArr;
}

Array.prototype.Intersection = function(arr){
    //Returns an array of elements that are present in both sets
    //{1,2,3,4,5}.Intersection({3,4,5,6,7})
    //returns: {3,4,5}
        var primArray = this;
        var secondArray = arr;
    var returnArr = new Array;
    var i = 0;
    while(i++<primArray.length){
        if(secondArray.contains(primArray[i])){
            returnArr.push(primArray[i]);
        }
    }
    return returnArr;
}

Array.prototype.Complement = function(arr){
    //Returns an array of elements that are only in the primary (calling) element
    //{1,2,3,4,5}.Complement({3,4,5,6,7})
    //return: {1,2}
        var primArray = this;
        var secondArray = arr;
    var i = primArray.length;
    while(i--){
        if(secondArray.contains(primArray[i])){
            primArray.splice(i, 1);
        }
    }
    return primArray;
}

Array.prototype.SymmetricDifference = function(arr){
    //Returns elements that are exclusive to each set
    //{1,2,3,4,5}.SymmetricDifference({3,4,5,6,7})
    //return: {1,2,6,7}
        var primArray = this;
        var secondArray = arr;
    var i = primArray.length;
    while(i--){
        if(secondArray.contains(primArray[i])){
            var indices = secondArray.getIndices(primArray[i]);
            primArray.splice(i, 1);
            var j=indices.length;
            while(j--){
                secondArray.splice(indices[j], 1);
            }
        }
    }
    var returnArr = primArray.concat(arr);
    return returnArr;
}

function run(){
     var Q = "A";
     var D = [1,2,3,4,5,6,7,8,9,10];
     var sets = {
          "A":[1,2,3],
          "B":[3,4,5],
          "C":[5,6,7]
     }
     var R = D;
     for(var el in sets){
          R = R.Complement(sets[el]);
     }
//if I alert D at this point I get 8,9,10 instead of 1,2,3,4,5,6,7,8,9,10 as I would expect? What am I missing here... It causes a problem when I perform D.Complement(R) later on
     document.write(R + "<br/>");
     R = R.Union(sets[Q]);
     document.write(R + "<br/>");
  //Here!  
     R = D.Complement(R);
     document.write(R);
}

</script>

</head>

<body onload="run()">

</body>
</html>

当我尝试获取域的补充和我新构建的集合时，一切都在努力到最后一点。我预计将获得[1,2,3,4,5,6,7,8,9,10]和[8,9,10,1,2,3]的补充，这将产生[4， 5,6,7]但是当我执行D.Complement（R）时，我的D变量似乎变成了[1,2,3]。这似乎发生在我执行的枚举之后。

我认为可能是因为我在我的函数中使用this.splice和arr.splice，当我将变量传递给函数时，它们作为指针传递，这意味着我实际上正在处理实际的内存位置。所以我然后使用primArray和secondArray来创建一个副本来处理...但问题仍在发生

非常感谢

Answer 1

所以我然后使用primArray和secondArray来创建一个副本来处理...但问题仍在发生

只是将它分配给一个变量并不会使它成为一个新数组，你仍然在处理传入的数组。你必须手动制作一个新的数组副本，方法是循环遍历它并复制每个索引或者通过加入和分裂。

我的自定义（Set Theory）Complements（）函数以某种方式损坏了我的数组数据？

1 个答案: