A Common-Sense Guide to Data Structures and Algorithms

A Practical Example

Let’s say that you are writing a JavaScript application, and somewhere in your code you find that you need to get the intersection between two arrays. The intersection is a list of all the values that occur in both of the arrays. For example, if you have the arrays [3, 1, 4, 2] and [4, 5, 3, 6], the intersection would be a third array, [3, 4], since both of those values are common to the two arrays.

JavaScript does not come with such a function built in, so we’ll have to create our own. Here’s one possible implementation:

function intersection(first_array, second_array){
    var result = [];

    for (var i = 0; i < first_array.length; i++) {
        for (var j = 0; j < second_array.length; j++) {
            if (first_array[i] ...