数组方法

reduce

累加

var arr1 = [1, 2, 3, 4]
// var result1 = arr.reduce((prev, next) => {
//   return prev + next
// }, 0)

var result1 = arr1.reduce((prev, next) => {
  return prev + next
})
console.log('result1', result1)
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累乘

var arr2 = [1, 2, 3, 4]
var result2 = arr2.reduce((prev, next) => {
  return prev * next
}, 1)
console.log('result2', result2)
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数组去重

var arr3 = [1, 2, 2, 3, 4]
var result3 = arr3.reduce((prev, next) => {
  if (!prev.includes(next)) {
    return [...prev, next]
  } else {
    return prev
  }
}, [])
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map

单数组

var arr1 = [1, 2, 3, 4]
var result1 = arr1.map(item => {
  return item + 1
})
console.log('result1', result1)
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数组中包含对象

var arr2 = [
  {
    age: 1,
    name: 'a'
  },
  {
    age: 2,
    name: 'b'
  },
  {
    age: 3,
    name: 'c'
  }
]

var result2 = arr2.map(item => {
  return {
    age: item.age + 1,
    name: item.name
  }
})
console.log('result2', result2)
var result3 = arr2.map(item => {
  return {
    age: item.age + 1
  }
})
console.log('arr2', arr2)
console.log('result3', result3)
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