手写一些方法

模拟new方法

function Otaku(name,age) {
    this.name = name;
    this.age = age;   
    this.habit = 'Games'
  }

  Otaku.prototype.strength = 60;
  Otaku.prototype.sayName = function () {
    console.log("I am " + this.name);
  };

  function myNew(fn, ...args) {
    const obj = Object.create(fn.prototype);
    const ret = fn.apply(obj, args); // ret有可能为null
    return typeof ret === "object" ? ret || obj : obj;
  }
  const person = myNew(Otaku,'甲',20);
  console.log(person,'person');

数组去重

  // 数组去重
  // 使用new set 
  // const uniqueArr = [...new Set(arr)];
  // const uniqueArr1 = Array.from(new Set(arr));

  // 使用reduce
  function unique(arr) {
    // 先排序，如果重复，则上一个下标的内容一样
    let sortArr = arr.sort()
    return sortArr.reduce((acc, current) => {
      if (acc[acc.length - 1] !== current) {
        acc.push(current);
      }
      return acc;
    }, [sortArr[0]]);
  }
  // let arr = [1,2,3,3,4,5,5]
  // let newArr = unique(arr);
  // console.log(newArr,'newArr');

  // 使用filter
  function unique1(arr) {
    return arr.filter((element, index, array) => {
      return array.indexOf(element) == index;
    });
  }

扁平化数组

// 使用reduce扁平化数组
  const flattenArr = (arr) => {
    return Array.isArray(arr) 
      ? arr.reduce((prev,current) => {
        return [...prev,...flattenArr(current)]
      },[]) 
      : [arr];
  }
  const newArr = flattenArr([[1,1],[2,3],12,32,[90]]);
  console.log(newArr); // [1, 1, 2, 3, 12, 32, 90]