[2, 10, 1].sort() // [1, 10, 2]
// 按数字大小排序
[2, 10, 1].sort((x, y) => x - y) // [1, 2, 10]

const array = [1, 1, 2]
// 多次使用
Array.prototype.unique = function() {
  return this.filter( (value, index, self) => { 
    return self.indexOf(value) === index
  })
}
array.unique()
// 单次使用
array.filter((v, i, arr) => arr.indexOf(v) === i)

#  先将数组转为无重复元素的 set 再转回 list
list(set(array))  # uniq

const test =  (a=1) => a
test() // 1
test(null) // null
test(undefined) // 1

// 简单比较数组是否相等
function arraysEqual(a1,a2) {
    /* WARNING: arrays must not contain {objects} or behavior may be undefined */
    return JSON.stringify(a1)==JSON.stringify(a2);
}

// map 返回默认值
const map = new Map ([
    [1,  'foo'],  // default
    [2,  'bar'],
    [3,  'baz'],
]);

const mapProxy = new Proxy(map, {
    get: function(target, id) {
        // Cast id to number:
        id = +id;
        return target.has(id) ? target.get(id) : target.get(1);
    },
});
console.log( mapProxy[3] ); // baz
console.log( mapProxy[10] ); // foo

// 快速创建多维数组
const arr = new Array(i).fill(0).map(a => new Array(j).fill(0))

// 配置git对大小写敏感
git config core.ignorecase false

uniq = arr => [...new Set(arr)]

'abc\n'.trim('a') // 'abc'
_.trim('abc\n', 'a') // 'bc\n'

>>> def foo(numbers=[]):
...     numbers.append(9)
...     return numbers
>>> foo()
[9]
>>> foo()
[9, 9]
>>> foo()
[9, 9, 9]

def foo(numbers=None):
    if numbers is None:
        numbers = []
    numbers.append(9)
    return numbers