Array.splice没有返回正确的输出

Question

我试图匹配两个数组，如果它们包含相同的值，它将从数组之一中删除元素。我尝试使用splice()方法。我尝试阅读，但是输出是：

new array ["SUGAR"]

但是，我想实现此输出：

["HYDROGENATED VEGETABLE↵OIL", "RAPESEED OIL", "PALM OIL", "SUNFLOWER OIL", "RAPESEED OIL", "PALM OIL"]

这是原始数组(unSafe(：

["SUGAR", "HYDROGENATED VEGETABLE↵OIL", "RAPESEED OIL", "PALM OIL", "SUNFLOWER OIL", "RAPESEED OIL", "PALM OIL"]

这是我的代码：

function breakArray() {
  let warning = this.navParams.get("warningResult");
  let unSafe = this.navParams.get("unSafeResult");
  console.log(unSafe);
  console.log(warning);
  for (var i = 0; i < warning.length; i++) {
    for (var j = 0; j < unSafe.length; j++) {
      if (warning[i] === unSafe[j]) {
        console.log('warning', i);
        console.log('unSafe', j);
        unSafe.splice(j, 1);
        console.log('new array', unSafe);
      }
    }
  }
}

Answer 1

您需要确保j为0。

// Original array.
var unsafe = ["SUGAR", "HYDROGENATED VEGETABLE↵OIL", "RAPESEED OIL", "PALM OIL", "SUNFLOWER OIL", "RAPESEED OIL", "PALM OIL"];
// Find the index of the item.
let removeIndexStart = unsafe.indexOf('SUGAR');
// Check if it exists.
if (removeIndexStart > -1) {
  // Returns the removed items (from index 0, removing 1 item)
  // and modifies the array in-place.
  var removed = unsafe.splice(removeIndexStart, 1);
  console.log('Removed:', JSON.stringify(removed, null, 2));
}
console.log('Modified:', JSON.stringify(unsafe, null, 2));

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---

尝试反向工作：

for (var i = warning.length - 1; i >= 0; i--) {

并在较大的数组上操作，这是您想要的。

warning.splice(i, 1);

let warning = ["SUGAR", "HYDROGENATED VEGETABLE↵OIL", "RAPESEED OIL", "PALM OIL", "SUNFLOWER OIL", "RAPESEED OIL", "PALM OIL"];
let unSafe =  ["SUGAR"];
breakArray(); // I would pass in arguments.
console.log('New array:', warning);
function breakArray() {
  for (var i = warning.length - 1; i >= 0; i--) {
    for (var j = 0; j < unSafe.length; j++) {
      if (warning[i] === unSafe[j]) {
        console.log('warning', i);
        console.log('unSafe', j);
        warning.splice(i, 1);
      }
    }
  }
}

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Answer 2

使用filter方法而不是splice。您不想在迭代的数组上拼接。

let unsafeArray = ["SUGAR", "HYDROGENATED VEGETABLE↵OIL", "RAPESEED OIL", "PALM OIL", "SUNFLOWER OIL", "RAPESEED OIL", "PALM OIL"];
let warningArray = ["SUGAR", "SUNFLOWER OIL"];
let filteredArray = unsafeArray;
warningArray.forEach(function (warningElement) {
  filteredArray = filteredArray.filter(function (unsafeElement) {
    return unsafeElement !== warningElement;
  });
});
console.log(filteredArray);

Answer 3

似乎工作正常。返回没有"警告"元素的数组。

function breakArray() {
  //let warning = this.navParams.get("warningResult");
  //let unSafe = this.navParams.get("unSafeResult");
  var warning = ["SUGAR"];
  var unSafe = ["SUGAR", "HYDROGENATED VEGETABLE↵OIL", "RAPESEED OIL", "PALM OIL", "SUNFLOWER OIL", "RAPESEED OIL", "PALM OIL"];
  //console.log(unSafe);
  //console.log(warning);
  for (var i = 0; i < warning.length; i++) {
    for (var j = 0; j < unSafe.length; j++) {
      if (warning[i] === unSafe[j]) {
        //console.log('warning', i);
        //console.log('unSafe', j);
        unSafe.splice(j, 1);
        console.log('new array', unSafe);
      }
    }
  }
}
breakArray();