Hello, in this JavaScript video, I am going to cover the map collection, map collection a data structure, which essentially allows you to store values that are assigned to a unique key and you will use the unique key to be able to retrieve those values to implement map is pretty simple to be fair, use the keyword var, as always, call it empty map equals new map, open close bracket, press colon. And now to set a value. You just do map got set. And let's say five part. So this the first part of the key second part of the value separated by a comma so the key is a key one. And also will internally get the value you do map dot get rid of console dot log you Let's just console log the map out first see what we get.
Map is empty. We reload it. So as you can see, we have a value there. Now, I'm actually going to keep that I'm going to see the overall structure of it. If you want to get an individual value with the doc gap. And now the key itself for the key one, printer HelloWorld once, then you can set another value.
And if I do something like just one, for example, the number one in the string, I'll say number one. More war happened if we do this. undefined, then my thinking, isn't that I look at the key one. No, he said the string one. That's something to bear in mind. You can actually have a key that is just a number, not a string.
So you could That's I forgot to change this, we change this to or should say to one that we're fine. But if I want to access the one, the key the string, you need to do this. So that's something to bear in mind. They are technically two individual keys and every store two different values at the string one and at the number one, so that's something to bear in mind. Another thing that you can do is basically check it out, turn it a certain, you know, key, do that by doing m p.com. and specify the key.
So let's say for say, one, yes, false. If I say no, the string one, because there is something there we get true. So that leads us to check. We actually have a particular key and obviously the value as well. Nothing on To show you is for creating MP, MP two equals new map. But what we're going to do is no quick curly braces.
And this will allow us to create a map with some initial key value pairs case you already know them. If you do know some of them, you can just put square brackets and then the key. So I'm just going to say key one. And you can just do single quotation marks as well I prefer double quotation marks, changes on the coolest value on the pro comma, and then if you want to put another value, you just put the square bracket or another key there we go. If we were to console, log it all out. So console log in to the scene structure.
And it's a very similar structure to this. It has obviously different keys and different values, but you can access them the same way. As we did here, we get as well. So that bunch of other methods that are available for manipulating Matt, from getting the values to get in and deleting keys, clearing out all the values, you can do all of that stuff, what I'll actually do is provide a link so you can see all of the extra functionality that you can utilize with map. One last thing I want to show you is how to actually loop over your entire map using a for loop. And that is really useful.
So at the moment, we've got what three value pair key value pairs here, we've got to hear. That's not too bad just to do dog dog, get like diff mind if you have 100 If you don't actually know the key necessarily, then in some sort of polling is useful. So let me demonstrate to with this, we're going to do is say for so we're gonna say school. And we're going to create a variable for for us us next us in a better at practice, that's fine. On that note I wish I was calling for this is fine, I'm off and then we say MP to come through and this gets all the entries that includes the key and the value. And what we're going to do now is we're going to console dot log and I will console log and using the backtick so this is a template literal.
If you haven't took the video I'd recommend taking a look at it now Going to put on square bracket zero. colon, just the separator for a data point doesn't really matter. And then dollar curly braces or the bracket 01, I should say, zero is where the key one is where the value is not zero yet three, k one, value one, k two, v two, k three and valley free. So that's how you loop over a map, which is very useful if you have a lot of value and he has that set number set up for that provide the link. If you have any more questions, feel free to pop me a message and I look forward to seeing you in the next video.