javascript - 识别两个数组之间的删除、附加和前置

Question

我试图找到两个数组之间的深层差异，如下所示

 var arr = [5,4,6,7,8,9]; var against = [1,2,4,5,6];

那么结果应该是

 appended = [7, 8, 9], prepended = [], removed = [1, 2]

我的逻辑已经用完了，这就是我尝试过的

 var prepend = [];
 var append = [];
 var removed = [];

 var len = against.length;

 while (len--) {
    var itm = listSplit[len];
    if (arr.indexOf(itm) === -1) {
       removed.push(len);
    } else if (itm < arr[0]) {
       // ??
    }
 }

我怎样才能找到这些值。给我一些逻辑上的想法来找到this .

Answer 1

其中一个解决方案可能是:

var arr = [7,8,9,5,4,6]; 
var against = [1,2,4,5,6];
// make a copy of the original array as appended
var appended = arr;
var removed =[];
var prepended =[];

for(var i=0;i<against.length;i++)
{  
    //if the element is not present in the original array, add it to removed.
    if(appended.indexOf(against[i]) == -1)
    {
        removed.push(against[i]);
    }
    else
    {
        //if it is already present, it was not appended, nor prepended, 
        //remove it from appended.
        appended.splice(appended.indexOf(against[i]),1);
    }
}
// one more loop to seperate the prepended from the appended values.
for(var j=0;j<appended.length;j++)
{   
    if(appended[j] < against[against.length-1])
    {
        prepended.push(appended.splice(j,1));
        j--;
    }
}

appended 数组中的最终值将是附加的值，而 removed 中的最终值将是被删除的值。保留的将是前置的。