如何基于JavaScript中的另一个数组比较和更新此数组？

Question

I am working on this challenge—Inventory update , on Free CodeCamp.com The challenge states:

Compare and update the inventory stored in a 2D array against a second 2D array of a fresh delivery. Update the current existing inventory item quantities (in arr1). If an item cannot be found, add the new item and quantity into the inventory array. The returned inventory array should be in alphabetical order by item.

function updateInventory(arr1, arr2) {
    for (var x = 0; x < arr1.length; x++) {

        for (var y = 0; y < arr2.length; y++) {

            if (arr1[x][1] === arr2[y][1]) {
                arr1[x][0] = arr2[y][0]  + arr1[x][0];
            }
        }
    }

 for(var j = 0; j < arr2.length; j++){

     var i = arr2[j][1];

     for(var k = 0; k < arr1.length; k++){
         var idx = arr1.indexOf(i);
          if(idx === -1){
             arr1.push(i);
          }
     }


}
return arr1;

}

When I try:

updateInventory([[21, "Bowling Ball"], [2, "Dirty Sock"], 
[1, "Hair Pin"], [5, "Microphone"]], [[2, "Hair Pin"], 
[3, "Half-Eaten Apple"], [67, "Bowling Ball"], 
[7, "Toothpaste"]]).length // I get 8 instead of 6

When I try:

updateInventory([[21, "Bowling Ball"], [2, "Dirty Sock"], 
[1, "Hair Pin"], [5, "Microphone"]], [[2, "Hair Pin"], 
[3, "Half-Eaten Apple"], [67, "Bowling Ball"], 
[7, "Toothpaste"]])

I get:

When I should get:

[[88, "Bowling Ball"], [2, "Dirty Sock"], [3, "Hair Pin"], 
[3, "Half-Eaten Apple"], [5, "Microphone"], [7, "Toothpaste"]]

I believe this is where my problem is...

for(var j = 0; j < arr2.length; j++){

         var i = arr2[j][1];

         for(var k = 0; k < arr1.length; k++){
             var idx = arr1.indexOf(i);
              if(idx === -1){
                 arr1.push(i);
              }
         }


    }

cause it's sort of working. But can anyone help with the alphabetical sorting part too? Thanks in advance!

Answer 1

Try this

function updateInventory(arr1, arr2) {
  for (var x = 0; x < arr1.length; x++) {

    for (var y = 0; y < arr2.length; y++) {

      if (arr1[x][1] === arr2[y][1]) {
        arr1[x][0] = arr2[y][0] + arr1[x][0];
      }
    }
  }

  for (var j = 0; j < arr2.length; j++) {

    var i = arr2[j][1];
    var found = 0;

    for (var k = 0; k < arr1.length; k++) {
      if (arr1[k][1] === arr2[j][1]){
        found = 1;}
    }
    if (found == 0)
      arr1.push(arr2[j]);
  }
  arr1.sort(compareSecondColumn);
  return arr1;

}

for sorting

function compareSecondColumn(a, b) {
    if (a[1] === b[1]) {
        return 0;
    }
    else {
        return (a[1] < b[1]) ? -1 : 1;
    }
}

Answer 2

You could do this as well, I know its been answered but just wanted to give it a go.

 Array.prototype.concatAll = function() { var results = []; this.forEach(function(subArray) { subArray.forEach(function(item) { results.push(item); }); }); return results; }; function updateInventory(arr1, arr2) { arr1.forEach(function(item) { for (var i = 0; i < arr2.length; i++) { if (item[1] === arr2[i][1]) { item[0] = item[0] + arr2[i][0]; } } }); arr1.forEach(function(item) { var tempArray = arr1.concatAll(); for (var e = 0; e < arr2.length; e++) { if (tempArray.indexOf(arr2[e][1]) === -1) { arr1.push(arr2[e]); } } }); arr1 = arr1.sort(function(a, b) { return (a[1] > b[1]) ? 1 : ((b[1] > a[1]) ? -1 : 0); }); alert(arr1); return arr1; } // Example inventory lists var curInv = [ [21, "Bowling Ball"], [2, "Dirty Sock"], [1, "Hair Pin"], [5, "Microphone"] ]; var newInv = [ [2, "Hair Pin"], [3, "Half-Eaten Apple"], [67, "Bowling Ball"], [7, "Toothpaste"] ]; updateInventory(curInv, newInv); 

Answer 3

You could use the built in array functions to make things a bit easier to understand. In my example I'm sure you could combine all the functions instead of altering the oldValues array.

var oldValues = [[21, "Bowling Ball"], [2, "Dirty Sock"], 
[1, "Hair Pin"], [5, "Microphone"]];

var newValues = [[2, "Hair Pin"], 
[3, "Half-Eaten Apple"], [67, "Bowling Ball"], 
[7, "Toothpaste"]];


newValues.forEach(function(nArr) {
  var i = 0;
  for(i; i < oldValues.length; i++) {
    if(oldValues[i][1] === nArr[1]) {
      oldValues[i] = nArr;
      return;
    }
  }
  oldValues.push(nArr);
});

oldValues.sort(function (ov, nv) {
  return ov[1] > nv[1];
}).forEach(function (v) {
  console.debug(v);
  $('#test').append('<li>[' + v[0] + ', ' + v[1] + ']</li>');
});

http://plnkr.co/edit/VNksR4eoDLEqU7TSoTj1?p=preview