Fill an array with consecutive numbers-CodePudding

I have an array that looks like this: [[3, Apple], [4, Banana], [7, Orange], [9, Pear]]

Now I'd like to add all missing numbers from 1 to 10 with empty entries where I have the fruit in the example, so that as result I'd have:

[
  [1, ],
  [2, ],
  [3, Apple],
  [4, Banana],
  [5, ],
  [6, ],
  [7, Orange],
  [8, ],
  [9, Pear]
  [10, ]
]

I'd share what I've tried so far, but I really am stuck at the beginning. Has anybody an idea how to accomplish that?

CodePudding user response：

You can start by creating an array with indexes only, and then iterate over your data to fill in the missing values from your input.

const data = [[3, "Apple"], [4, "Banana"], [7, "Orange"], [9, "Pear"]]

const result = data.reduce((result, [id, val]) => {
  result[id - 1].push(val);
  return result;
}, Array.from({length: 10}, (_, i)=> [i   1]))

console.log(result);

Here 2nd argument of the reduce function is an array of length 10, filled with 1 element arrays, where element is an index 1.

The first argument is a function called on every element of your input data, that modifies the 2nd argument.

CodePudding user response：

let result = []
let fruits = [[3, 'Apple'], [4, 'Banana'], [7, 'Orange'], [9, 'Pear']]

let fruitsObject = Object.fromEntries(fruits)

for (let i = 1; i<=10; i  ){


    result.push(fruitsObject[i] ? [i, fruitsObject[i]] : [i]) 
}

console.log(result)