Skip to main content

Objects and Hash tables in JavaScript

Hash tables share many similarities with objects, like storing data in key-value pairs and having the same syntax to add and retrieve elements. We can think of hash tables as a dictionary where you can look up a word definition using just the letter/letters, except for hashing the key string into a series of numbers that will be used to access the value in the array that holds the values.

So in general, we should use hash tables instead of objects because they provide a very fast access to the data stored within.

Comments

Post a Comment

Popular posts from this blog

How Does While Loop Work?

I think that everybody knows what while means, right? Imagine you want to do something for a 'while' :) You're gonna need to repeat that thing for a number of times; limited or unlimited. For example, if you wanted to do something from your daily life like drinking water 7 times each day you're going to do a task (i.e process) for seven times and you're going to decrease that number each time you drink water. Before you start drinking, the number of times would be seven. So,  a condition to check to stop drinking would be great. Like when the number of times is less than seven -> continue doing this process (drinking water) and increasing the number of times you have drank  by one. Once the number of times reaches seven -> stop this process. Hope that helped clear the picture even if it was a little bit.
Post a Comment
Read more

Big O Notation

Big O Notation is a mathematical expression that describes how much time an algorithm takes to run according to the size of it's inputs; mostly concerned about the worst case scenario. Types: 1- Constant Time O(1): On this order, regardless of the number of items, the iterations(time) are constant. Example: const getFirstItem = items =>    items[0]; getFirstITem([1, 2, 3, 4]);  // 1 (one iteration) getFirstItem(['b', 'd', 'g']);   // 'b' (one iteration) 2- Linear Time O(n): On this order, the worst case grows with the number of items. Example: Javascript's built in function indexOf, it loops over an array to find the  correct index of the passed element. The worst case is looping over the whole array. [1, 2, 4, 9, 23, 12].indexOf(12); 3- Quadratic Time O(n ^ 2): For this order, the worst case time is the square of the number of inputs. It grows exponentially according to the number of inputs. Example: Using nested loo...
Post a Comment
Read more

Relational Databases

Relational databases are, well... a collection of data items that have relations between them. These relations are made by associating a one table's primary key with another table's foreign key. It is a great advancement from the old long table that was used to store data which was inefficient in terms of search, memory and space.  And as for normalization; it means a process in which tables are structured to eliminate redundancy and repetition among data and the CRUD operations side-effects. And as a direct result we improve the performance of our queries. An example of a relational database would be two tables; one for student and the other for school. Both of these tables have a column for the school id, and so we make a connection between by assigning the first one as a primary key and the other as foreign key.
Post a Comment
Read more