javascript

With the help of the browser’s LocalStorage, we can keep track of the number of visits of a user on the website or a particular webpage. Based on this data, customized alerts, messages or information can be shown to the user.

[Read More]

In the last post I showed how can we plot a form whose data is all dynamic, coming from a backend API. Continuing from there, say we have again a totally dynamic set of fields coming from a backend API. It has some fields that are conditionally linked to another field. [Read More]

We need to plot a form whose entire fields are coming from the backend. Since the fields are not known in advance, we cannot add them statically. The data about each field, such as its id to save with, name, validations, etc. all comes in the API response too.

For the given scenario, I have used React Hook Form. The demo and example code for a dynamic questionnaire is shared below.

[Read More]

When you visit your own blog or website, Google Analytics still tracks it as a view, which kind of corrupt your stats a little. If you want to check your site and keep the analytics data clean and legitimate, you must somehow exclude yourself from all the visits on all the pages. [Read More]

Say we have a an array of objects with start and end times in each. This could be anything, ranging from work experience (the way LinkedIn shows per job), to education, to sports career. We want to sum all these small experiences, excluding overlapping and idle times, and give out the total duration, which can further be converted into years, months, or days. [Read More]

Detecting the country and region of the visiting user on the browser is certainly possible using JavaScript alone, without using any third-party geolocation service such as ipstack. The only consideration: It may not be accurate, and depend on the timezone selected by the user on their system, which can be changed. But since hardly anybody changes their system-auto-detected timezone nowadays (except for testing, which I have shown below), it is a good enough and cheap detection method for non-critical use cases.

[Read More]

We know that there is no true random number. The best we get is pseudo-random number, which comes from a seed value. I was wondering if I could get a random number without using Math.random() function of JavaScript. So I developed an algorithm of my own, which is a few lines of code that works by keeping, updating, and shifting a seed array in the state. [Read More]

We have two similar JavaScript objects and are interested in finding which key(s), if any, have changed at the first level. A key in the object could hold any data type in its value, including array and object, and it could also be deeply nested. The change could mean anything, such as added, added to, removed, removed from, modified, shuffled, etc.

You may require this kind of key identification in cases where you compare the old and new states, such as previous and new filters, and figure out what exactly changed.

[Read More]

Token Bucket is a rate-limiting algorithm in which there is a bucket that gets refilled at a particular rate with tokens. To perform an action, one or more tokens can be taken out or redeemed from this bucket. When there are no more tokens left, the action cannot be performed until the bucket is refilled and further tokens are available. [Read More]

Recently I came across a problem where I needed to perform two different sets of operations throughout the application for two types of users. The trouble was:

1. I needed to turn on or off an operation based on certain condition, which would only be known once the user was logged in, not at the beginning.

[Read More]