JavaScript如何从一个数组中删除第二个数组中包含的元素[duplicate]

Question

我误解了如何删除数组中与另一个数组有匹配元素的元素。

示例：

const items = ['first', 'second', 'third']
const secondItems = ['first', 'second']

预期：

console.log(items) | 'third'
console.log(secondItems) | 'first', 'second

希望能举一些例子来说明如何做到这一点。用两个forEach或filter和checking语句尝试了很多次，但我总是得到错误的结果。

Answer 1

items.filter(x => !secondItems.includes(x))

刚刚在浏览器控制台中尝试过，它可以工作。

Answer 2

这可以通过以下方式解决：

const items = ['first', 'second', 'third'];
const secondItems = ['first', 'second'];


const filteredBySecondItems = items.filter(function(item) {

  // For item in items array, check if there is a match
  // in secondItems. If there is no match, allow it
  // to be included in the returned list
  return secondItems.indexOf(item) === -1 

})

console.log(filteredBySecondItems) // [ 'third' ]

Answer 3

只需使用Array.prototype.filter（）方法：

const items = ['first', 'second', 'third']
const secondItems = ['first', 'second']

console.log(items.filter(i => !secondItems.includes(i)))
console.log(secondItems.filter(i => items.includes(i)))