Paginate Javascript array

Question

I am trying to write a Javascript function that takes an array, page_size and page_number as parameters and returns an array that mimics paginated results:

paginate: function (array, page_size, page_number) {   return result; } 

so for example when:

array = [1, 2, 3, 4, 5], page size = 2, page_number = 2, 

the function should return: [3, 4].

Any ideas would be appreciated.

Answer 1

You can use Array.prototype.slice and just supply the params for (start, end).

function paginate(array, page_size, page_number) {    // human-readable page numbers usually start with 1, so we reduce 1 in the first argument    return array.slice((page_number - 1) * page_size, page_number * page_size);  }    console.log(paginate([1, 2, 3, 4, 5, 6], 2, 2));  console.log(paginate([1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11], 4, 1));

Answer 2

Here's a solution with reduce():

function paginate (arr, size) {    return arr.reduce((acc, val, i) => {      let idx = Math.floor(i / size)      let page = acc[idx] || (acc[idx] = [])      page.push(val)        return acc    }, [])  }    let array = [1, 2, 3, 4, 5]  let page_size = 2  let pages = paginate(array, page_size)    console.log(pages)    // all pages  console.log(pages[1]) // second page

It returns an array of pages so you can get a certain page, or loop through all of them.