Good day posse and welcome to this offbeat javascript instructional exercise presently I do as of now have a nonconcurrent js seminar on youtube yet that is presently about four years of age so i'm putting up a more modern series which is directly from my udemy current javascript course also, it will cover things like the get programming interface guarantees async and weight just as the entirety of the nuts and bolts and building squares of what offbeat code is so I trust you appreciate it and on the off chance that you need to take the full udemy course the connection will be down underneath in the portrayal [Music] nonconcurrent javascript is one of the most significant pieces of the language since it oversees how we perform undertakings that require some investment to do like mentioning information from a data set or then again from a programming interface and chances are in case you're making a genuine javascript application then you will utilize offbeat code sooner or later to do these sorts of things so in a very shortsighted nutshell nonconcurrent code is code that can begin every so often finish afterward be that as it may, before we talk more about nonconcurrent code we should above all else comprehend its partner simultaneous code so javascript by its very nature is a coordinated language also, that essentially implies that javascript can execute just a single proclamation at an at once to base so for instance in a javascript record we could have three articulations also, every assertion is run thus now line two can't begin before line one is wrapped up furthermore, line three can't begin before line two is done so it executes these each in turn in request presently you may hear javascript being called a solitary strung language what's more, that basically implies something very similar thing a string resembles an requested arrangement of explanations and as it were one of those assertions can run at a time so this is the essence of coordinated code each assertion being executed in turn after each other presently with this picture of coordinated code as a primary concern a solitary string and just one explanation executing at an at once situation we need to call a lot of javascript capacities in a record a portion of these capacities do speedy seemingly insignificant details like log something to a control center yet one of them needs to make an organization solicitation to a information base on another worker some place to get some information presently this could require a few seconds to finish perhaps less perhaps more so in a coordinated programming world since only one articulation can run at an at once of information slows down the program this is known as impeding code in light of the fact that it hinders the following line of code from running until it gets the information back and this work is finished after those a few seconds now in this case you may think well OK two seconds isn't that long to stand by however what on the off chance that you have different capacities to get information then that could before long be five to six seconds or six to seven seconds furthermore, it would obstruct the remainder of the code under from running until these things are finished so this is a defeat of simultaneous code also, this is the place where nonconcurrent code becomes an integral factor to take care of us so we realize that running our capacities simultaneously with regards to task that sets aside some effort to finish is presumably then, at that point not the most ideal approach to work right so recollect the definition I initially gave you of nonconcurrent code to begin something now and finish it later this is the example we for the most part need to follow when running errands that set aside some effort to do like organization demands for information to a data set or a programming interface so envision we have a similar sort of succession of capacity calls or then again proclamations just this time rather than this being some sort of coordinated work to demand information we utilize an offbeat work all things considered furthermore, this implies the capacity can begin from time to time finish later when the information has returned from any place we get it from presently since this capacity is wrapping up later what we normally do is pass this capacity or this assertion some sort of callback work as a boundary and afterward that callback work is the thing that runs and wraps up later on once the solicitation is finished furthermore, the information returns so how could this be all functioning admirably we have our line of capacity brings in the code again which executed one at a time so first this one then this one, etc presently recollect consistently javascript can just execute each thing in turn yet, this time when we get to the solicitation work here we are utilizing an offbeat capacity to demand our outer information what this implies is that the program takes that solicitation and it handles it outside of the extent of this single string in another piece of the program it moreover takes a callback capacity and puts it to one side too with the goal that it knows to execute this later on when the information returns so in light of the fact that this organization demand has been taken out of this string and is presently running in a distinctive piece of the program javascript can continue down the line also, run the excess capacities meanwhile this is as yet going on the demand for information so it proceeds through these capacities and afterward when it gets the information back from the organization demand what's more, when the remainder of the capacities have been executed then, at that point we're permitted to call this callback work what's more, finish this unique capacity so this is the core of nonconcurrent programming beginning something now which can be done later and it makes our code non-obstructing in light of the fact that the remainder of the capacities here they can run while the solicitation is being made now this clarification is an exceptionally oversimplified one and there are different things at play like the occasion circle and the call stack which we've not examined yet, I think to dig into that at this moment would be somewhat overpowering and I think this image of painted ought to be sufficient until further notice to comprehend the overall thought of nonconcurrent code so presently we know a minimal about what that is also, what offbeat code we should examine a model alright then, at that point so ideally now you comprehend essentially the fundamental guideline of offbeat code and how javascript has a solitary string and goes through one work at a time or one proclamation at a time so I need to do a speedy demo of this in activity a fast straightforward one so the main thing i'm going to do is glue in four console logs so in the event that I save this we know presently that javascript is going to execute these each in turn through and through what's more, in the control center we get one two three four true to form presently what i'm going to do in the center is i'm going to do a set break and we've seen this previously it's the place where we're passing a capacity and that capacity fires after a certain measure of time that we indicate so how about we do the capacity most importantly what's more, inside here we'll console.log what's more, we'll say the callback work terminated OK and we need to fire this after all around we should simply say 2 000 milliseconds so that is two seconds so this here this is intended to copy some sort of organization demand that takes time to do as such envision this is going out to get information and it requires two seconds to do then, at that point when it returns it's going to fire a callback work it's a similar kind of thing for this situation we're not getting information we're simply holding up two seconds to imitate that solicitation and afterward we're terminating this so this here this is a coordinated code in real life it's going to start when the record runs it's going to pause two seconds and afterward it's going to wrap up later by terminating this callback work presently is this going to obstruct the remainder of the code will it go one two then, at that point stand by two seconds and fire this then, at that point 3 4 or then again will it not block the code well I recently said that this is nonconcurrent so it doesn't hinder the code and i'll show you that in the event that I save it we see one two three four then, at that point following two seconds we get this so if you envision that picture of a string I showed you previously furthermore, these things are on it fires this then, at that point this then, at that point this and afterward it holds up two seconds here and passes the callback work elsewhere and afterward it fires this then this and following two seconds the callback work is added to the base here and this is the place where it fires toward the end after one two three four so this doesn't impede the code so later on rather than utilizing set break we'll utilize genuine http network demands for information however this sort of lays everything out of how everything functions it will be a similar rule so presently we know the overall guideline behind it of nonconcurrent code i'm demonstrating how to really make network demands. Thank you
