编写函数createArray(holder, length)返回长度为length，成员都是holder的数组

superwyk

方法一

function createArray(holder, length){
    const arr = new Array(length);
    arr.fill(holder);
    return arr;
}

方法二

// es6方法
function createArray(holder, length){
    const arr = [];
    while(length--){
        arr.push(holder);
    }
    return arr;
}

febcat

方法一

const createArray = (holder, length) => {
  let newHolder = [];

  while (length > 0) {
    newHolder.push(holder);
    length--;
  }

  return newHolder;
};

console.log("createArray", JSON.stringify(createArray(1, 5)));

方法二

const createArray2 = (holder, length) => {
  let holderType = Object.prototype.toString.call(holder);
  let holderStr = holder + "";
  let regStr = `(${holderStr})`;
  let holderInit = res => {
    switch (holderType) {
      case "[object Number]":
        return res.map(item => item - "");
      case "[object Null]":
        return res.map(() => null);
      case "[object Boolean]":
        return res.map(item => JSON.parse(item));
      default:
        return res;
    }
  };

console.log("createArray2", JSON.stringify(createArray2("true", 5)));

Mtd

// fill() 方法用一个固定值填充一个数组中从起始索引到终止索引内的全部元素。不包括终止索引

// es6
function createArray(holder, length) {
  let arr = new Array(length);
  arr.fill(holder);
  
  return arr;
}

function createArray(holder, length) {
  let arr = [];
  while (length--) {
    arr.push(holder)
  } 
  
  return arr;
}

Wlxm

1. Array(length).fill(holder)
2. new Array(length).fill(holder)
3. for循环填充