如何迭代一些数组并生成哈希

Question

我有以下数组：

[1, 2, 3, 4, 5]

我需要根据上面的数组创建一个哈希，如下所示：

cars = { models: [ { 1: '', 2: '', 3: '', 4: '', 5: '' } ] }

我怎样才能创建这个哈希并访问一些像这样的值：

cars['models]['2']

Answer 1

cars['model']['2'] 无法匹配您显示的数据结构，因为 models 是一个数组而不是一个 javascript 对象。

你必须使用cars.model[0]['2'] 或cars['model'][0]['2']

const createHash=arr=>
{
  let model = []
  model[0] = Object.fromEntries(arr.map(n => [n, 'x'])) 
  return {model}
}


let cars =  createHash ( [1, 2, 3, 4, 5] )

console.log ( cars.model[0]['2'] )
console.log ( 'cars :', JSON.stringify( cars ) )

如果要匹配cars['model']['2']，则必须将数据结构更改为cars : {"model":{"1":"y","2":"y","3":"y","4":"y","5":"y"}}

// different structure :
const createHash=arr=>
{
  let model = Object.fromEntries(arr.map(n => [n, ''])) 
  return {model}
}


let cars =  createHash ( [1, 2, 3, 4, 5] )

cars['model']['4'] = 'A'

console.log( "cars['model']['4'] ->", cars['model']['4'])

console.log ( 'cars :', JSON.stringify( cars ) )