var array=new Array();

var array=[];

var array=[1,2,3];
console.log(array instanceof Array) //true

console.log(Array.isArray(array)) //true

var array=[1,2,3];

var arrayToString=array.toString();
var arrayValueOf=array.valueOf();
var arrayToLocalString=array.toLocaleString();

    console.log(arrayToString);//    1,2,3
console.log(arrayValueOf);//[1, 2, 3]
console.log(arrayToLocalString);//1,2,3

var arr1=['q','w','e'];
var arr2=['h','u','o'];
document.write(arr1.concat(arr2)); //q,w,e,h,u,o

var arr3=['h','e','l','l','o'];
console.log(arr3.slice(1));//e,l,l,o
console.log(arr3.slice(-4));//e,l,l,o
arr3.slice(-4)===arr3.slice(1);//true

//從第一項開始刪除兩項
var splice_arr1=['h','e','l','l','o'];
   console.log(splice_arr1.splice(1,2))//返回的是被刪除的項組成的數(shù)組["e", "l"]
   //從第二項后插入三項old
   var splice_arr2=['h','e','l','l','o'];
   var removed=splice_arr2.splice(2,0,"K","K");
   console.log(splice_arr2);//["h", "e", "K", "K", "l", "l", "o"]              
   console.log(removed)//返回的是一個空數(shù)組
   //替換
   var removed=splice_arr3.splice(2,2,"P","P");
console.log(splice_arr3);//["h", "e", "P", "P", "o"]
console.log(removed)//返回的是被替換的值["l", "l"]

// indexOf()  從前往后找
// lastIndexOf()  從后往前找
var index_arr=['h','e','l','l','o'];
var indexOf_arr=index_arr.indexOf('l');
console.log('原數(shù)組:',index_arr)//原數(shù)組不變
console.log('返回值:',indexOf_arr)//返回值是第一個查到位置的索引值2

var index_arr2=['h','e','l','l','o'];
var indexOf_arr2=index_arr2.lastIndexOf('l');
console.log('原數(shù)組:',index_arr2)//原數(shù)組不變
console.log('返回值:',indexOf_arr2)//返回值是第一個查到位置的索引值3

var numbers=[1,2,3,4,5,6,7,8,9,0,9,8,7,65,5,4,33,21,1,1,23,3,4];
var everyArr=numbers.every(function(it, index ,arr){
    if(it>9){
        return true;
    }
})
console.log(everyArr);///false

var someArr=numbers.some(function(it, index ,arr){
        return (it > 9) ;
})
console.log(someArr);///true

var numbers=[1,2,3,4,5,6,7,8,9,0,9,8,7,65,5,4,33,21,1,1,23,3,4];
var forEachArr=numbers.forEach(function(it, index ,arr){
    var it=it*100;
    console.log(it)
})
//無返回值

var numbers=[1,2,3,4,5,6,7,8,9,0,9,8,7,65,5,4,33,21,1,1,23,3,4];
var filterArr=numbers.filter(function(it, index ,arr){
    if(it>10){
        return it;
    }
})
console.log(filterArr);//[65, 33, 21, 23]
//返回返回值組成的新數(shù)組

var numbers=[1,2,3,4,5,6,7,8,9,0,9,8,7,65,5,4,33,21,1,1,23,3,4];
var mapArray=numbers.map(function(it, index ,arr){
    var it=it*100;
    return it;
})
console.log(mapArray)
//[100, 200, 300, 400, 500, 600, 700, 800, 900, 0, 900, 800, 700, 6500, 500, 400, 3300, 2100, 100, 100, 2300, 300, 400]
//返回返回值組成的新數(shù)組

var numbers=[1,2,3,4,5,6,7,8,9,0,9,8,7,65,5,4,33,21,1,1,23,3,4];
var allArray=numbers.reduce(function(prev,cur,index,arr){
    return (prev+cur);
})
console.log(allArray);//229

var numbers=[1,2,3,4,5,6,7,8,9,0,9,8,7,65,5,4,33,21,1,1,23,3,4];
var allArrayRight=numbers.reduceRight(function(prev,cur,index,arr){
    return (prev+cur);
})
console.log(allArrayRight);//229