Cannot read property 'push' of undefined when combining arrays

Question

When pushing an array\'s contents to another array I get

\"Uncaught TypeError: Cannot read property \'push\' of undefined\" error in this snippet.

Answer 1

I fixed in the below way with typescript

1. Define and initialize firest

pageNumbers: number[] = [];

2. than populate it

   for (let i = 1; i < 201; i++) {
       this.pageNumbers.push(i);
   }