Summary of common methods of arrays

1. Array name.push(array)//Add at the end to return a new array after adding
2. Array name.pop(array)//Delete at the end
3. Array name.shift(not requiredPass parameters)//Delete the header
4. Array name.unshift(added data)//Add the header
5. Array name.reverse(array)//Flip and return to the reversed
6. Array name. splice (start index, how many, data to be inserted) // used for array interception delete insertion array (splice will affect the original array)

splice method example:var arr=[1,2,3,4,5,6,7,8]      let ad=arr.splice(0,3)//Intercept 3 from the 0 index, you can let ad receive the intercepted dataYou can also not receive and print arr, you will find that three data have been deletedconsole.log(ad);

     
7. 数组.slice(开始索引，结束索引) 使用slice 截取数组  该方法  不会影响原始数组

8. Array sorting:
Array name.sort(function(a,b){return a-b}) positive order
Array name.sort(function(a,b){return b-a}) flashback

9. Array to String join()

arr=[1,2,3,4]arr.join()prints as 1-2-3-4array name.join('-') 

10. Array concatenation concat()

let arr=[1,2,3,4]arr.concat[5,6]prints as [1, 2, 3, 4, 5, 6]

11. Array name.indexOf(data) Find whether the data exists in the array and return the subscript otherwise return -1
//Filter the array

12. filter() array filter

Array.filter(function(item,index,arr){Return the returned array that matches the filter conditions})

This method returns a new filtered array

13. every() determines whether each item meets the conditions

Array.every(function(item,index,arr){return what is returnedThe method returns a boolean value})

14 .some() Determines whether an item in the array satisfies the condition

Array.some(function(item,index,arr){return what is returnedReturns a boolean value})

15. Array name.map() Array mapping
The simple understanding of map is to modify the original array loop operation and then define a variable to receive the returned content
It calls the function for each element of the array, andReturns an array of results.
Example:

let arr = [1,2,3]let arr2 = arr.map(item => item*2)console.log(arr2)//map traverse the new array returned after modificationConsole.log(arr)//Original arrayBy printing, you will find that using the map method does not modify the contents of the original array but returns a new array

16. includes fuzzy query

 includes fuzzy querieslet arr = ['Tom', 'jian', 'jierui', 'kk']let strVal2= arr.filter(item =>item.includes('k'))console.log(strVal2);//This method can find the content that meets the conditions in the array. Generally, it is used as a fuzzy search function in the search box with filter filtering.

   
17.forEach loops through the array
 

Array name.forEach((item,index) => {Each content of the item arrayindex subscript})