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Javascript – TypeScript: How to insert a multidimensional array into another multidimensional array?

A two-dimensional array is to be extended (No new one is to be created):

let array:number[][] = [
    [5, 6],
];

For this we have two more two-dimensional arrays a1 and a2:

let a1:number[][] = [[1, 2], [3, 4]];
let a2:number[][] = [[7, 8], [9, 10]];

The goal is now to insert a1 at the beginning and a2 at the end of array:

array.unshift(a1);
array.push(a2);

The syntax is not permitted and the following errors occur:

Argument of type 'number[][]' is not assignable to parameter of type 'number[]'.
Type 'number[]' is not assignable to type 'number'.

The expected result is as follows:

[
    [1, 2],
    [3, 4],
    [5, 6],
    [7, 8],
    [9, 10]
];

Does TypeScript/Javascript provide a way to insert the arrays without having to iterate and unshift/push element by element?

Please not:
Since the existing array can become very large, I would like to avoid copies (e.g. by concat or something similar).

Tags:

2

Answers


  1. 0

    why not sort the array after adding new element using array.sort

    let array = [
    [5, 6],
];

let a1 = [[1, 2], [3, 4]];
let a2 = [[7, 8], [9, 10]];

array.unshift(...a1);
array.push(...a2);

array = array.sort((a, b) => a[0]-b[0])
console.log(array);
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  2. 0

    You’re almost there. You just need to use the spread syntax.

    let array: number[][] = [[5, 6]];

let a1: number[][] = [
  [1, 2],
  [3, 4],
];
let a2: number[][] = [
  [7, 8],
  [9, 10],
];

array.unshift(...a1);
array.push(...a2);

console.log(array);
// [[1, 2], [3, 4], [5, 6], [7, 8], [9, 10]]

    TypeScript Playground

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