const arr = [1, 1, '1', 17, true, true, false, false, 'true', 'a', {}, {}]; // => [1, '1', 17, true, false, 'true', 'a', {}, {}]

const res1 = Array.from(new Set(arr));

const unique1 = arr => {   let len = arr.length;   for (let i = 0; i < len; i++) {     for (let j = i + 1; j < len; j++) {       if (arr[i] === arr[j]) {         arr.splice(j, 1);         // 每删除一个树，j--保证j的值经过自加后不变。同时，len--，减少循环次数提升性能        len--;         j--;       }     }   }   return arr;}

const unique2 = arr => {   const res = [];   for (let i = 0; i < arr.length; i++) {     if (res.indexOf(arr[i]) === -1) res.push(arr[i]);   }   return res;}

const unique3 = arr => {   const res = [];   for (let i = 0; i < arr.length; i++) {     if (!res.includes(arr[i])) res.push(arr[i]);   }   return res;}

const unique4 = arr => {   return arr.filter((item, index) => {     return arr.indexOf(item) === index;   }); }

const unique5 = arr => {   const map = new Map();   const res = [];   for (let i = 0; i < arr.length; i++) {     if (!map.has(arr[i])) {       map.set(arr[i], true)       res.push(arr[i]);     }   }   return res;}