Js数组的map,filter,reduce,every,some方法
var arr=[1,2,3,4,5,6];
res = arr.map(function(x){return x*x})
[1, 4, 9, 16, 25, 36]
res = arr.filter(function(x){return x<3})
[1, 2]
res = arr.reduce(function(a,b){return a+b})
21
res = arr.every(function(x){return x>7})
false
res = arr.some(function(x){return x<3})
true