常用的陣列操作方法

陣列新增：push（後面新增），unshift（前面新增）

let arr =

["1"
,"2"
,"3"];
console.
log(arr.
push(0
,4))
;// 新增後的陣列長度:5
console.
log(arr)
;//["1", "2", "3", 0, 4]
let arr =
["1"
,"2"
,"3"];
console.
log(arr.
unshift(0
,4))
;// 新增後的陣列長度:5
console.
log(arr)
;//[ 0, 4,"1", "2", "3"]

let arr =

["1"
,"2"
,"3"
,"4"
,"5"];
console.
log(arr.
pop())
;// 原陣列陣列長度:5
console.
log(arr)
;//["1", "2", "3", "4"]
let arr =
["1"
,"2"
,"3"
,"4"
,"5"];
console.
log(arr.
shift()
);// 原陣列陣列長度:5
console.
log(arr)
;//["2", "3", "4", "5"];

index:陣列開始下標

length: 替換/刪除的長度

key:替換的值,預設為空

//刪除

let arr =
["a"
,"b"
,"c"];
console.
log(arr.
splice(1
,1))
;// 刪除的值："b"
console.
log(arr)
;// ["a","c"]
//替換
let arr =
["a"
,"b"
,"c"];
console.
log(arr.
splice(1
,1,1
));// 替換的值："b"
console.
log(arr)
;// ["a","1","c"]
//新增
let arr =
["a"
,"b"
,"c"];
console.
log(arr.
splice(1
,0,"你好"))
;// 空陣列
console.
log(arr)
;// ["a", "你好", "b", "c"]

//方法一

let arr =[1
,2,3
,4,5
];let arr1 = arr.
concat([
1,2]
);console.
log(arr)
;// [1,2,3,4,5]
console.
log(arr1)
;// [1,2,3,4,5,1,2]
//方法二
var arr1=
['a'
,'b'
,'c'
,'d'];
var arr2=
['d'];
var arr3=
['e'
,'f'];
var dd=
[...arr1,
...arr2,
...arr3]
;console.
log(dd)
;//["a", "b", "c", "d", "d", "e", "f"]

let str =

'12345'
;let arr = str.
split(''
);console.
log(arr)
;// ["1", "2", "3", "4", "5"]

let arr =[2

,10,6
,1,4
,22,3
]let arr1 = arr.
sort
((a, b)
=>a - b)
console.
log(arr1)
// [1, 2, 3, 4, 6, 10, 22]
let arr2 = arr.
sort
((a, b)
=>b-a) 
console.
log(arr2)
// [22, 10, 6, 4, 3, 2, 1]

let arr =[1

,2,3
,4,5
]let arr1 = arr.
reverse()
console.
log(arr1)
// [5,4,3,2,1]

var array =[1

,2,3
,3,4
,5];
//方法一if(
newset
(array)
.size !== array.length)
else
//方法二
let ary = array.
from
(new
set(array)
)console.
log(ary)
// [1, 2, 3, 4, 5]

以上方法不適合陣列物件或陣列包陣列的情況

//foreach

let arr =[1
,2,3
,4,5
]arr.
foreach
((value,index,array)
=>
index:
$array:$`
)})// value:1 index:0 array:1,2,3,4,5
// value:2 index:1 array:1,2,3,4,5
// value:3 index:2 array:1,2,3,4,5
// value:4 index:3 array:1,2,3,4,5
// value:5 index:4 array:1,2,3,4,5
//map
let arr =[1
,2,3
,4,5
];let info = arr.
map(
(value, index, array)
=>;}
);console.
log(info)
;

arr.foreach()是和for迴圈一樣，是代替for。arr.map()是修改陣列其中的資料，並返回新的資料。

arr.foreach() 沒有return； arr.map() 有return

let arr =[1

,2,3
,4,5
];let arr1 = arr.
filter
((value, index)
=>})
;console.
log(arr1)
;// [4, 5]

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JavaScript常用陣列操作方法

concat 方法用於連線兩個或多個陣列。該方法不會改變現有的陣列，僅會返回被連線陣列的乙個副本。var arr1 1,2,3 var arr2 4,5 var arr3 arr1.concat arr2 console.log arr1 1,2,3 console.log arr3 1,2,3,4...

js常用陣列操作方法

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