In this lesson we touch on just a few of the Array methods:
Concat creates a shallow copy of an existing array that includes any arguments you pass to it. In this lesson, we look at using concat for adding additional values to an array then cover some more useful features such as accepting other arrays as arguments & how to chain concat with other array methods such as
One very common operation in programming is to iterate through an Array's contents, apply a function to each item, and create a new array containing the results. For example, let's say you wanted to loop through an array of stock objects and select only the name for display on screen. In this lesson we will demonstrate how to use the Array's map method to easily perform this operation with less code than a loop would require.
One very common operation in programming is to iterate through an Array's contents, apply a test function to each item, and create a new array containing only those items the passed the test. For example, let's say you wanted to loop through an array of stocks and select only those with the price larger than a certain value. In this lesson we will demonstrate how to use the Array's filter method to easily perform this operation with less code than a loop would require.
Both map and filter do not modify the array. Instead they return a new array of the results. Because both map and filter return Arrays, we can chain these functions together to build complex array transformations with very little code. Finally we can consume the newly created array using forEach. In this lesson, we will learn how to build nontrivial programs without using any loops at all.
In addition to flat Arrays, programmers must often deal with nested Arrays. For example let's say we have an Array of stock exchanges, each of which is represented by an array of all the stocks listed on that exchange. If we were looking for a stock that matched a certain criteria, we would first need to loop through all of the exchanges, and then all of the stocks within.
In these situations, most developers would nest two loops. However in this lesson we will write a new Array function "concatAll" which will automatically flatten nested arrays buy one dimension. This will remove the need to ever use a nested loop to flatten a nested array.