Question

我正在尝试理解下面的“寻求和毁灭”挑战。

任务：将为您提供一个初始数组（驱逐舰函数中的第一个参数），后跟一个或多个参数。从初始数组中删除与这些参数具有相同值的所有元素。

This is the initial code below:
function destroyer(arr) {
  // Remove all the values
  return arr;
}

destroyer([1, 2, 3, 1, 2, 3], 2, 3);

经过几次（真的）尝试并查看其他人的代码后，我能够解决该任务。但是，我认为这更不幸运了。我在下面复制了我的代码，但我希望有人可以为我澄清一些事情。

下面的代码传递我是否在iterateThroughArray函数中返回val或args。那是为什么？
如果我应该将所有参数与第一个参数进行比较，那么在这段代码中我指出了什么？我一直在想我需要拼接第一个参数来比较所有其他参数，或者为参数[0]创建一个变量。非常感谢您提供的任何指导！

function destroyer(arr) {
      var args = Array.from(arguments); //this also converts them to an array
       var iterateThroughArr = function (val) {
         if (args.indexOf(val) ===-1){
            return args;
          }
       };
       return arr.filter(iterateThroughArr);
    }

Answer 1

这可能听起来很多，但这是我的解释

function destroyer(arr) {
      var args = Array.from(arguments); //Here arr is converted to [Array(6),2,3]
      //console.log(args)
    /*   var iterateThroughArr = function (val) {
         if (args.indexOf(val) ===-1){
            return args;
          }
       };
     
     return arr.filter(iterateThroughArr);
     */
     
     // to make more clear the above code can be rewritten as below
     var arr = arr.filter(function (val) {
          console.log("args = "+ args + " val = " + val + " indexOf(val) "  + args.indexOf(val) )
         // here you are itterating through each arr val which in this case is[1,2,3,1,2,3]
         // if you dont believe me uncomment the next console.log() and see the output
        // console.log(val) 
         if (args.indexOf(val) ===-1){
          // here is where the magic happens
          // Now you are checking if val exisists by using a builtin method called .indexOf()
          // In general, .indexOf() returns -1 if a value does not exist within an array
          //Below is working example
          /* var array = [1,2,3,4,5]
            console.log(array.indexOf(1)) // 0 since it is located at index 0
            console.log(array.indexOf(5)) // 4 since it is located at index 4
            console.log(array.indexOf(10))  // -1 since it does not exisit 
             */ 
           // Therefore, if value passes the above if statement 
          //then that means it doesnot exisit on args([Array(6),2,3])
           //which as a result will be included on the filtered array
           
            return args;
          }
       });
       
       return arr;
     
    }
    
    
 var val =    destroyer([1, 2, 3, 1, 2, 3], 2, 3);
 //console.log(val)

基本上，您需要了解的是过滤器的工作原理以及.indexOf的工作原理。有关更多详细信息，请访问Mozilla文档：.indexOf()和.filter()

Answer 2

尝试一下：

function destroyer(arr) {
  // arr1 is equal to the array inside arr
  var arr1 = arr.slice(arguments);
  // arr2 becomes an array with the arguments 2 & 3
  var arr2 = Array.prototype.slice.call(arguments, 1);
  // this function compares the two and returns an array with elements not equal to the arguments
  return arr1.concat(arr2).filter(function (item) {
    return !arr1.includes(item) || !arr2.includes(item)
  })
}


destroyer([1, 2, 3, 1, 2, 3], 2, 3);

Seek and Destroy Freecode阵营的争论挑战

2 个答案: