var arr = [1, 2, 4, 5, 6, 9, 10, 15];
var r = arr.filter(function (x) {
 return x % 2 !== 0;
});
r; // [1, 5, 9, 15]

var arr = ['A', '', 'B', null, undefined, 'C', ' '];
var r = arr.filter(function (s) {
 return s && s.trim(); // 注：IE9(不包含IE9)以下的版本没有trim()方法
});
arr; // ['A', 'B', 'C']

var arr = ['A', 'B', 'C'];
var r = arr.filter(function (element, index, self) {
 console.log(element); // 依次打印'A', 'B', 'C'
 console.log(index); // 依次打印0, 1, 2
 console.log(self); // self就是变量arr
 return true;
});

var r,
 arr = ['apple', 'strawberry', 'banana', 'pear', 'apple', 'orange', 'orange', 'strawberry'];

r = arr.filter(function (element, index, self) {
 return self.indexOf(element) === index;
});

console.log(r.toString());