数组方法
//toString() 将数组转换为字符串;不改变原数组
var fruits = ["Banana", "Orange", "Apple", "Mango"];
var fru = fruits.toString();
console.log(fruits);//["Banana", "Orange", "Apple", "Mango"] 不改变原数组
console.log(fru);//Banana, Orange, Apple, Mango
//join()方法 将数组元素合并成一个字符串，可以规定隔离符号;不改变原数组
var fruits1 = ["Banana","Orange","Apple","Mango"];
var fru1 = fruits1.join("*");
console.log(fruits1);//["Banana", "Orange", "Apple", "Mango"] 不改变原数组
console.log(fru1);//Banana*Orange*Apple*Mango
// pop() 从数组中删除最后一个元素；改变了原数组
// push() 向数组末尾添加一个新元素；改变了原数组
var fruits2 = ["Banana","Orange","Apple","Mango"];
var fru2 = fruits2.push("Kiwi");
console.log(fruits2);//["Banana","Orange","Apple","Mango","Kiwi"]
console.log(fru2);//输出改变后的数组长度 5
var fru2 = fruits2.pop();
console.log(fruits2);//["Banana","Orange","Apple","Mango"]
console.log(fru2);//输出删除元素"Kiwi"
// shift() 从数组中删除第一个元素；改变了原数组
// unshift() 向数组首位添加一个新元素；改变了原数组
var fruits3 = ["Banana","Orange","Apple","Mango"];
var fru3 = fruits3.shift();
console.log(fruits3);//["Orange","Apple","Mango"]
console.log(fru3);//输出移除的元素"Banana"
var fru3 = fruits3.unshift("Kiwi");
console.log(fruits3);//["Kiwi","Orange","Apple","Mango"]
console.log(fru3);//输出改变后的数组长度4
//splice(a,b,c) 第一个参数a定义了应添加新元素的位置（拼接）;第二个参数（b）定义应删除多少元素;其余参数（c）定义要添加的新元素。
var fruits3 = ["Banana","Orange","Apple","Mango"];
var fru3 = fruits3.splice(2,1,"Lemon","Tea");
console.log(fru3);//输出删除的数组元素["Apple"]
console.log(fruits3);//["Banana","Orange","Lemon","Tea","Mango"]
//也可以直接移除元素，如：
fruits3.splice(1,2);
console.log(fruits3);//["Banana","Tea","Mango"]
//concat() 合并数组；不会改变现有数组
var arr1 = ["Cecilie", "Lone"];
var arr2 = ["Emil", "Tobias", "Linus"];
var arr3 = ["Robin", "Morgan"];
var newArr = arr1.concat(arr2, arr3);
console.log(newArr);
//slice() 裁剪数组;不改变原数组；第一个参数是裁剪起始位置的位置，第二个参数是裁剪结束位置的位置（可省略）
var fruits4 = ["Banana","Orange","Apple","Mango"];
var fru4 = fruits4.slice(1,3);
console.log(fruits4);//["Banana","Orange","Apple","Mango"]
console.log(fru4);//["Orange","Apple"]