Summary of es6 filter() array filtering method (with code)

This article brings you a summary of the es6 filter() array filtering method (with code). It has certain reference value. Friends in need can refer to it. I hope it will be helpful to you.

Array.every(x=>x) must satisfy each one.

Array.some(x=>x) must satisfy one of them.

Array.find(findIndex), returns the first value that meets the conditions.

Array.filter (filter into a new array)

Array methods are divided into two categories

1) Change the original array

push, pop, shift, unshift, sort, reverse, splice

2) Do not change the original array concat, join-->

split, toStringpush: add data starting from the last bit of the array

pop: Cut the last digit of the array

shift: Cut the first digit of the array

unshift: Add the number to the first digit of the array

reverse: Put Reverse the original array

splice:arr.splice(start from the number, intercept the length, add new data at the cut)

concat: connect join: return string

slice: Intercept arr.slice (intercept from this to this)

es6 filter() Summary of array filtering method
1. Create an array and determine whether a certain item exists in the array Value

var newarr = [
  { num: 1, val: 'ceshi', flag: 'aa' },
  { num: 2, val: 'ceshi2', flag: 'aa2'  }
]
console.log(newarr.filter(item => item.num===2 ))

2. You can also use the above method to filter out those with num of 2 and leave those with num of 1

var newarr = [
  { num: 1, val: 'ceshi', flag: 'aa' },
  { num: 2, val: 'ceshi2', flag: 'aa2'  }
]
console.log(newarr.filter(item => item.num!=2 ))

3. Remove empty arrays, empty strings, undefined, and null

var arr = ['1','2',undefined, '3.jpg',undefined]
var newArr = arr.filter(item => item)
console.log(newArr)

var arr = ['1','2',null, '3.jpg',null]
var newArr = arr.filter(item => item)
console.log(newArr)

//空字符串里面不能包含空格
var arr = ['1','2','', '3.jpg','']
var newArr = arr.filter(item => item)
console.log(newArr)

4. Remove non-conforming items from the array

var arr = [20,30,50, 96,50]
var newArr = arr.filter(item => item>40)  
console.log(newArr)

5. Filter non-conforming items

var arr = ['10','12','23','44','42']
var newArr = arr.filter(item => item.indexOf(&#39;2&#39;)<0) 
console.log(newArr)

6. Remove duplicates from the array

var arr = [1, 2, 2, 3, 4, 5, 5, 6, 7, 7,8,8,0,8,6,3,4,56,2];
var arr2 = arr.filter((x, index,self)=>self.indexOf(x)===index)  
console.log(arr2); //[1, 2, 3, 4, 5, 6, 7, 8, 0, 56]

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