将数组转为对象(指定key)

const arrayToObject = (arr, key) => arr.reduce((a, b) => ({ ...a, [b[key]]: b }), {});

// eg:
arrayToObject([{id:6,name:'张三'}, {id:70,name:'里斯'}], 'id')
/*
{
    "6": {
        "id": 6,
        "name": "张三"
    },
    "70": {
        "id": 70,
        "name": "里斯"
    }
}
*/

数组去重

export const unique = (arr) => {
  if (Array.hasOwnProperty('from')) { 
    return Array.from(new Set(arr));
  } else { 
    var n = {},
    r = []; 
    for (var i = 0; i < arr.length; i++) {
      if (!n[arr[i]]) { 
        n[arr[i]] = true;
        r.push(arr[i]);
      }
    }
    return r; 
  }
}

随机打乱数组(洗牌算法)

export const shuffle = (arr) => { 
  let result = [], random;
  while (arr.length > 0) { 
    random = Math.floor(Math.random() * arr.length);
    result.push(arr[random]);
    arr.splice(random, 1) ;
  } 
  return result;
}