1.arr.toSring() => 数组转为字符串
var arr = [1,2,3];
arr.toSring();
// arr => “1,2,3”
2.arr.join("-") = > 数组以分隔符转为字符串
var arr = [1,2,3];
arr.join("+");
//arr => "1+2+3"
3.arr.pop() => 删除数组中最后一个元素(返回已删除的元素)
var arr = [1,2,3];
var last = arr.pop();
// last => 3
// arr => [1,2]
4.arr.push("lastValue") => 向数组末尾添加一个新元素(返回新数组的长度)
var arr = [1,2];
var length = arr.push(3);
//arr => [1,2,3]
//length => 3
5.arr.shift() => 删除数组中的首个元素(返回已删除的元素）
var arr = [1,2,3];
var first = arr.shift();
//arr => [2,3]
//first => 1
6.arr.unshift("fistValue") => 在数组开头添加一个新元素(返回新数组的长度)
var arr = [1,2,3];
var length = arr.unshift(0);
//arr => [0,1,2,3]
//length => 4
7.arr[arr.length] = "lastValue" 通过索引(下标)访问/修改数组
var arr = [0,1,2,3];
var first = arr[0];
arr[3] = 4;
arr[arr.length] = "last"
//fist => 0
//arr[3] => 4
//arr => [0,1,2,4]
//arr = > [0,1,2,4,"last"]
8. delete arr[index] => 根据数组下标删除元素(返回true)
var arr = [0,1,2,4,"last"];
var empty = delete arr[3];
//empty => true
//arr => [0,1,2,empty,"last"]
9.splice(index,deleteNum,addValue) => 根据下标添加/删除数组(返回已删除的)
addValue : 添加新元素，可省略
var arr = [1,2,3]
var delete = arr.splice(1,1,"last");
//从数组下标为1开始删除1个，添加"last"
//delete => [2]
//arr => [1,"last",3]
10.newArr = arr3.concat(arr1,arr2) => 合并/连接数组(不更改原数组，返回新数组)
arr1 = [1,2,3];
arr2 = [4,5,6]
arr3 = [7,8,9];
newArr = arr3.concat(arr1,arr2,[1,2]);
//newArr => [7,8,9,1,2,3,4,5,6,1,2]
11.var cutDate = slice(start,end) => 返回选取下标之间的新数组，不包含end下标元素，不修改原数组,可省略end参数，默认选取到最后。
arr1 = [1,2,3];
sliceData = [1];
//sliceDate => 1
12.sort() => 以字母由a-z/数字由0到9顺序对数组进行排序
arr = [1,3,2];
arr.sort();
//arr => [1,2,3]
arr1 = ["g","e","a"];
arr1.sort();
//arr1 => ["a","e","g"]
如果数字按照字符串来排序，则 "25" 大于 "100"，因为 "2" 大于 "1"。
可{比值函数}来修正此问题：
//原理
当 sort() 函数比较两个值时，会将值发送到比较函数，并根据所返回的值（负、零或正值）对这些值进行排序。
//升序
var points = [40, 100, 1, 5, 25, 10];
points.sort(function(a, b){return a - b});
//如果返回负值则把a排在b前面
// points[0] => 最低值
// points[points.length-1] => 最高值
//降序
var points = [40, 100, 1, 5, 25, 10];
points.sort(function(a, b){return b - a});
//如果返回负值则把a排在b前面
// points[0] => 最高值
// points[points.length-1] => 最低值
//以随机顺序排序数组
var points = [40, 100, 1, 5, 25, 10];
points.sort(function(a, b){return 0.5 - Math.random()});
13.reverse() => 反转数组中的元素
arr = [1,3,2];
arr.reverse ();
//arr=> [2,3,1];
arr.reverse();
//arr => [1,3,2]
14.查找数组中的最高/最小值
max = Math.max.apply(null,arr)
min = Math.min.apply(null,arr)
