Is it possible to map only a portion of an array? (Array.map())

Question

I am building a project using React.js as a front-end framework. On one particular page I am displaying a full data set to the user. I have an Array which contains this full

Answer 1

There is no version of the map() function that only maps a partial of the array.

You could use .map() in conjunction with .filter().

You get the index of the current element as the second arg of map and if you have a variable for current page and page size you can quite easily filter the right page from your array without having to really slice it up.

var currentPage = 1;
var pageSize = 25;

dataArray.filter(function(elt, index) {

    var upperThreshold = currentPage * pageSize;
    var lowerThreshold = currentPage * pageSize - pageSize;

    return index < upperThreshold && index > lowerThreshold;

});