Js Array-隨記

JavaScript

1.數據類型：boolean    number    string    array    function    undefined    NaN

定義數組：var arr = [2,"2",true];

console.log(arr[2]);                    (.................................................................//arr[2]索引)

for (var i =0; i < arr.lenght; i++){            (..................................arr.length:數組長度)

        console.lod(arr[i]);

}                                                 (............................................................................//2   2    true)

。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。

數組

arr.push()  往數組末尾添加元素

例：var arr = [2,"2",true];

for (var i = 0; i < 3; i++){

        arr.push(i);

}

console.log(arr);...........................Array(6)........arr = [2,"2",true,0,1,2]

arr.unshift()    往開頭添加元素

例：var arr = [2,"2",true];

for (var i = 0; i < 3; i++){

        arr.unshift(i);

}

console.log(arr);...........................Array(6)........arr = [0,1,2,2,"2",true,]

arr.pop()刪除數組最後一個元素

例：var arr = [2,"2",true];

        arr.pop();

console.log(arr);...........................Array(2)........arr = [2,"2"]

arr.shift()    刪除開頭的元素

var arr = [2,"2",true];

  arr.shift();

console.log(arr);...........................Array(2)........arr = ["2",true]

arr.join()    功能：把數組中的所有元素放入一個字符串

                   返回值：字符串

var arr = [2,"2",true];

var array =  arr.join(",");

 

console.log(arr);...........................[2,"2",true]    數組

console.log(array);...........................2,2,true    字符串

console.log(typeof(array));..........................String