1, the push ()

Adds new content to the end of the array

Parameter: item to add. Multiple passes are separated by commas and can be of any data type

Return value: The length of the new array

Whether to change the original array: change

let ary1 = [12.34.26];

ary1.push(100); // Return a new length

length=4console.log(ary1)// result is [12,34,26,100]

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2, pop ()

Deletes the last item of the array

Parameters: no

Return value: deleted item

Whether to change the original array: change

let ary2 = [108.112.39.10];

ary2.pop();// The last item removed is 10

console.log(ary2);/ / [108, 112, 39]

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3, the shift ()

Deletes the first item of the array

Parameters: no

Return value: deleted item

Whether to change the original array: change

let ary3 = [0.108.112.39];

ary3.shift();// The first item removed is 0

console.log(ary3);/ / [108, 112, 39]

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4, unshift ()

Adds new content to the top of the array

Parameter: Item to be added, separated by ‘,’

Return value: The length of the new array

Whether to change the original array: change

let ary4 = ['c'.'d'];

ary4.unshift('a'.'b');

console.log(ary4);//["a", "b", "c", "d"]
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5, slice ()

Find out part of the content according to the conditions

Parameters:

Array.slice (n, m) from index n to m (without m)

Array.slice (n) if the second argument is omitted, the search continues until the end

Array.slice (0) output the original content, can implement array cloning

Array. slice(-n,-m) Slice supports negative arguments. -1 is the last entry and -2 is the penultimate entry from the last entry

Return value: Returns a new array

Whether to change the original array: No change

let ary5 = [1.2.3.4.5.6.7.8.9];

/ / the console. The log (ary5. Slice (2, 8)); [3, 4, 5, 6, 7, 8] [3, 4, 5, 6, 7, 8]

//console.log(ary5.slice(0));

console.log(ary5.slice(-2, -1));/ / [8]
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6, splice ()

Add, delete, or modify an array

Add: ary.splice(n,0,m) deletes 0 items from index n, and inserts M or more items before index n

Return an empty array

Change: ary.splice(n,x,m) deletes x numbers from index n, m replaces the deleted parts

Delete the original content and replace it with new content

Delete: ary.splice(n,m) deletes m items from index n

(If the second argument is omitted, it is removed from n to the end)

Returns deleted new array, original array changed

/ / add

let ary6_z = [33.44.55.66.77.88];

ary6_z.splice(2.0.'a'.'b')

console.log(ary6_z);// [33, 44, "a", "b", 55, 66, 77, 88]

 
/ / modify

let ary6_x = [33.44.55.66.77.88];

ary6_x.splice(1.2.'x'.'y')

console.log(ary6_x);// [33, "x", "y", 66, 77, 88]

 
/ / delete

let ary6_s = [33.44.55.66.77.88];

/ / the console log (ary6 splice (3, 2)) / / [66, 77]

console.log(ary6_s.splice(3));/ / [66, 77, 88]

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7, the join ()

Concatenates each item of the array into a string using the specified delimiter

Argument: Delimiter specified (if omitted, comma is used as delimiter)

Return value: concatenated string

Whether to change the original array: No change

let ary7 = [1.2.3];

console.log(ary7.join(', '));//1, 2, 3
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8, concat ()

Join two or more arrays

Arguments: Arguments can be concrete values or array objects. It can be as many as you want

Return value: Returns the new array after joining

Whether to change the original array: No change

let ary8 = ['you'];

let ary80 = ary8.concat('good');

console.log(ary80);//[" you ", "ok "]
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9, indexOf ()

Checks the index of the first occurrence of the current value in the array

Parameter: array.indexof (item,start) item: the element to search for start: the position in the string at which the search begins

Return value: the first search index, if no, -1 is returned

Whether to change the original array: No change

let ary9 = ['a'.'b'.'c'.'d'.'e'.'a'.'f'];  

console.log(ary9.indexOf('c'));/ / 2

console.log(ary9.indexOf('a'.3))/ / 5
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10, lastIndexOf ()

Checks the index of the last occurrence of the current value in the array

Parameter: array.lastIndexof (item,start) item: the element to search for start: the position in the string at which the search begins

Return value: the first search index, if no, -1 is returned

Whether to change the original array: No change

let ary10 = ['a'.'b'.'c'.'d'.'e'.'a'.'f'];  

console.log(ary10.lastIndexOf('c'));/ / 2

console.log(ary10.lastIndexOf('f'.1))/ / 1
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11, includes ()

Checks whether an array contains a specified value

Parameter: specifies the content

Return value: Boolean

Whether to change the original array: No change

let ary13 = ['a'.'b'.'c'.'d'];

console.log(ary13.includes('c'));//true

console.log(ary13.includes(2));//false
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12, the sort ()

Sort the elements of an array (by default, sort from smallest to largest and by string)

Parameter: Optional (function) Specifies the sort rule. The default sort order is alphabetical ascending

Return value: new sorted array

Whether to change the original array: change

Sort can only handle numeric sorts up to 10 (single digits) without passing an argument

let ary11 = [32.44.23.54.90.12.9];

       ary11.sort(function(a,b){        // return a-b; // Result [9, 12, 23, 32, 44, 54, 90]

    // return b-a; [90, 54, 44, 32, 23, 12, 9]})

console.log(ary11);
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13 and reverse ()

Arrange the array upside down

Parameters: no

Return value: new array in reverse order

Whether to change the original array: change

let ary12 = [6.8.10.12];

console.log(ary12.reverse());/ / [12, 10, 8, 6]
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14 and the forEach ()

Loop through each item in the set

ForEach (function(item,index,ary){}) item: each item index: the index ary: the current array

Returned value: None

Whether to change the original array: No change

ForEach: “continue” and “break” cannot be used in forEach. ForEach: “skip” cannot be used in forEach.

let ary14 = ['a'.'b'.'c'.'d'];

let item = ary14.forEach(function(item,index,ary){

       console.log(item,index,ary);
  })
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So that’s what the common array methods are.