10 Essential JavaScript Functions You Need To Know

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JavaScript Functions

Javascript is one of the most popular and commonly used programming languages in the world right now. It is a versatile language which is just one of the reasons why it is so popular. It can be used to program webpages, desktop and server programs, applications, etc. Even other programs and databases like MongoDB and CouchDB use Javascript. in this article we will discuss few essential Javascript functions that can really make a difference between a beginner and a professional Javascript developer.

Still, Javascript has come a long way since it was developed. In the early days, a developer would only need to know a few simple functions for nearly all type features. This was because browser vendors implemented features differently. However, over time as the need required, Javascript has evolved and now utilizes a number of features that do more than just the basic tasks.
Now Javascript features can help developers build something without spending hours writing code. Javascript utilizes a number of pre-built functions that make tasks easier. These functions also include resuable code, which means that using this allows the developers to build something without writing the same part of code over and over again.

Following are the 10 essential Javascript functions

1. decodeURI

Often with programming languages, the whitespaces, spaces and similar characters in a URI can cause parsing problems. This can result in a number of errors. Hence, these spaces are commonly replaced with the relevant Unicode characters, typically by using JavaScript’s in-built function. However, the decodeURI function can be used to identify and decode the standard components of the URI.
2. debounce
The debounce function allows for a callback function to be used more than once per given time frame. This comes in handy when assigning a callback function to frequently-firing events. The debounce function can really help speed up events. It can be used with a scroll, resize, key* event.
3. poll
The poll function is another function that really makes things easier. It allows one to periodically “poll” the server and request new information (such as new messages or emails).The server then responds and sends the new information down to the client. This is done automatically and again and again over a certain period of time, so that the user does not have to manually check for updates.
4. once
The once function allows a developer to run a given functionality only once. This function is quite similar to an onload event. It runs one time for the page and not again for that page, and thus avoids duplicate initialization. The once function does not require the function being called to be declared a certain way because it is used when calling a function and not when defining the function. It can be used with any existing functions- including those within external libraries.
5. onload
Each time a web page is loaded, the browser processes the code from top to bottom order. However, the onload function allows the developer to change this order. It gives the developer more control over the order of code execution and lets them decide the sequence of code execution. Each time the web page is loaded, the specific function will be executed.
6. toString
Developers often ask users to validate a value by confirming the value input by them, but for this they must display the values as string. This is regardless of their data types. The toString function can be helpful here as it allows the developer to showcase the values of a variety of objects as characters. This certainly makes things easier. However, the toString function cannot manipulate the value converted into string or allow developers to make any changes to the original value or data type to the variable.
7. getAbsoluteUrl
As the name suggests, getAbsoluteUrl allows one to get an absolute URL. Getting an absolute URL from a variable string is not that easy, which is why this function really comes in handy. It acts as an alternative to the URL constructor which can be tricky to use if the required arguments are not provided regularly. The getAbsoluteUrl allows one to bypass that entirely and is an easier way for getting an absolute URL from a string input.
8. isNative
isNative is a very handy function that allows one to tell whether or not a function is native or not. While it may seem irrelevant, it is quite important actually. Knowing if a function is native or not helps the developer decide whether or not to risk overriding it. Knowing the risks beforehand really puts things in perspective, and if you do end up messing something up down the line, this could help you figure out why.
9. insertRule
insertRule allows one to insert a CSS rule into the current stylesheet. This function is handy as it lets you change the stylesheet halfway down the line; you no longer have to go back and customize the whole stylesheet. In JavaScript, this function can be used for grabbing a NodeList from a selector, giving it a particular style, and then setting that to the selector. Thus you no longer need to account for styling each element that may match that selector forever more.
10. matchesSelector
The matchesSelector function allows one to check if an element is of a given selector match. Thus you can validate the element before moving forward. This reduces the number of errors that you may get down the line. If you cannot validate the element, then you can make changes here and now, rather than guess where the error is coming from down the line.
JavaScript is a very functional language, which it why it continues to be so popular. These functions can really help you expand your knowledge of JavaScript and really improve your programs. Nearly every developer knows JavaScript to some extent, and you have to since as so many programs are either built on JavaScript or use some component that is built on JavaScript. Knowing these functions can really help you showcase yourself as an expert on JavaScript, not to mention they do help make some things easier, and anything that makes things easier is always a plus.

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