TypeScript - replace many elements in array

In TypeScript it is not intuitive at first time how to replace many elements in array. Replace operation can be achieved with Array.prototype.splice method. This article is focused on how to do it.

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//    index:              0    1    2    3    4    5    6

const array: string[] = ['a', 'b', 'c', 'd', 'e', 'f', 'g'];

​

// removing 4 elements sice 1st index position

// inserting sice 1st index position 4 elements

array.splice(1, 4, 'new item 1', 'new item 2', 'new item 3', 'new item N');

​

console.log(array);

Output:

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[

  'a',

  'new item 1',

  'new item 2',

  'new item 3',

  'new item N',

  'f',

  'g'

]

Notes about Array.prototype.splice method:

• takes as first argument index of begining of removed elements
• takes as second argument number of removed elements
• takes as third and next arguments added elements

1. Array.prototype.splice method - MDN Docs