Answer 1

var arr = [ [1, 2, 2], [3, 4, 5, 5], [6, 7, 8, 9, [11, 12, [12, 13, [14] ] ] ], 10];
function flatten(arr) {

    while (arr.some(item => Array.isArray(item))) {
        arr = [].concat(...arr);
    }

    return arr;
}
Array.from(new Set(flatten(arr))).sort((a, b) => {
 return a - b
})

Answer 2

Promise.prototype.then = function(onResolved, onRejected) {
...
    if (self.state === 'resolved') {
        return new Promise(function(resolve, reject) {
            try {
                var x = onResolved(self.data);
                // 如果onResolved的返回值是一个Promise对象，直接取它的结果做为promise2的结果
                if (x instanceof Promise) x.then(resolve, reject);
                resolve(x);
...

这里var x = onResolved(self.data)直接把值算出来了, 异步不就变成同步了么, 计算onResolved一定会卡住的

Answer 3

我们逻辑一般都是这样写的
return new Promise (resolve, reject)->
Promise.resolve()
.then ()->
// if error
return Promise.reject(error)
.then ()->
// 不会执行了
.then ()->
.catch (error)->
reject(error)