如何基于动态变量将元素推入数组 [英] How to push elements into array based on dynamic variable

问题描述

我有一个对象，我想用对象属性填充数组，并根据其值重复每个属性多次.一个例子:

I have an object and I want to fill an array with the object property and repeat each property a number of times, based on its value. An example:

obj = {
   watches: 3
   rings: 1
}
// => ['watches', 'watches', 'watches', 'rings']

以下是我到目前为止的内容.我很难确定如何根据关联的值重复每个属性?

Below is what I have so far. I'm having a hard time figuring how to repeat each property based on the associated value?

function arrayBuilder(obj) {
  let objToArr = [];

  for (let [property, value] of Object.entries(obj)) {
    objToArr.push(property);
  }
  return objToArr;
}

console.log(arrayBuilder({watches: 3, rings: 1}));
// => [ 'watches', 'rings' ]

推荐答案

您可以使用

You can use Array.flatMap() (note the support) with Array.fill():

const obj = {
   watches: 3,
   rings: 1
}

const result = Object.entries(obj).flatMap(([k, v]) => Array(v).fill(k));

console.log(result);

或 Array.reduce() 和数组传播，如果不支持flatMap:

Or Array.reduce() with array spread, if flatMap is not supported:

const obj = {
   watches: 3,
   rings: 1
}

const result = Object.entries(obj)
  .reduce((r, [k, v]) => [...r, ...Array(v).fill(k)], []); // or r.concat(Array(v).fill(k)) instead of the spread

console.log(result);

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