1 00:00:00,210 --> 00:00:05,970 You might also get a task like this creative function to replace parameters in your realm. 2 00:00:06,180 --> 00:00:12,420 And actually, this is a real world task because here we have an initial euro like it is generated in 3 00:00:12,420 --> 00:00:15,120 all rounders for all frontend frameworks. 4 00:00:15,390 --> 00:00:22,170 And in this case, we have like initial euro less both SLAs and here Colin Powell's posted slash common 5 00:00:22,170 --> 00:00:29,100 slash column Commentated, which means this two parameters with Collins will be replaced by ads at some 6 00:00:29,100 --> 00:00:29,850 point later. 7 00:00:30,060 --> 00:00:35,820 And actually, we must try to function replace params in the URL where we can throw inside the URL with 8 00:00:35,820 --> 00:00:38,970 such structure and our array of replacements. 9 00:00:39,240 --> 00:00:45,450 And as you can see inside, every single object we must provide from and tool, for example, from Paul's 10 00:00:45,450 --> 00:00:51,960 2D means that we must replace Colin posted with a do and here commentator with a three. 11 00:00:52,230 --> 00:00:54,540 And of course, this function must be generic. 12 00:00:54,690 --> 00:00:59,400 It is not only for posts and comments, but any replacements inside the URL. 13 00:01:02,800 --> 00:01:08,050 And actually, before we will start, Solomon, I want to show you one more thing how you can think 14 00:01:08,080 --> 00:01:09,520 about solving problems. 15 00:01:09,760 --> 00:01:15,250 For example, you can write something like To-Do list and in this case were trying to think in steps 16 00:01:15,400 --> 00:01:17,230 regarding what we want to implement. 17 00:01:17,500 --> 00:01:19,780 For example, what will be the first step here? 18 00:01:20,050 --> 00:01:25,210 As you see, we have an array of our replacements, which actually means we have a function of with 19 00:01:25,210 --> 00:01:25,960 two arguments. 20 00:01:26,170 --> 00:01:31,680 And actually, we want to move through every single replacement and to play this replacement to our 21 00:01:31,810 --> 00:01:32,260 as well. 22 00:01:32,470 --> 00:01:36,610 So actually, here we can write go through replacements. 23 00:01:37,450 --> 00:01:43,270 And the second point will be maybe replace parts of each. 24 00:01:43,570 --> 00:01:47,620 The replacements and the last thing will be here, return in your scene. 25 00:01:47,950 --> 00:01:53,530 And this list in this case might sound like an obvious thing, but it can help if you write something 26 00:01:53,530 --> 00:02:00,220 like this to implement more complex logic and actually directly want to implement a correct solution. 27 00:02:00,430 --> 00:02:03,530 And we can use reviews for this because it's huge. 28 00:02:03,550 --> 00:02:04,600 Our code best. 29 00:02:04,780 --> 00:02:10,180 But I also want to show you the single problem that you might don't actually hear but want to create 30 00:02:10,180 --> 00:02:12,730 our function, replace programs in general. 31 00:02:12,910 --> 00:02:16,630 And we're getting here, you as well and our list of replacements. 32 00:02:16,780 --> 00:02:20,800 And actually, what we want to do here is reduce for our replacements. 33 00:02:21,040 --> 00:02:22,990 So replacements door to reduce. 34 00:02:23,170 --> 00:02:27,610 And here we have a function with accumulator and each of replacement. 35 00:02:27,820 --> 00:02:33,970 And this initial value we have here all year round because this is what we want to change now here inside 36 00:02:33,970 --> 00:02:36,970 the function, we must return updated strain. 37 00:02:37,120 --> 00:02:41,200 And for this, we can use a plain JavaScript function, which is called replace. 38 00:02:41,530 --> 00:02:43,480 And actually, here you might write it. 39 00:02:43,480 --> 00:02:44,290 Run like this. 40 00:02:44,470 --> 00:02:46,420 You can think, OK, I have a URL. 41 00:02:46,600 --> 00:02:47,800 We can simply right here. 42 00:02:47,800 --> 00:02:50,290 Your cell equals your cell to replace. 43 00:02:50,590 --> 00:02:51,320 And here we are. 44 00:02:51,430 --> 00:02:55,720 Place and first a full column plus replacement not from. 45 00:02:55,870 --> 00:02:58,710 And we're changing it to a replacement DOD tool. 46 00:02:58,780 --> 00:02:59,350 This is it. 47 00:02:59,590 --> 00:03:02,320 And after this, we want to return our URL. 48 00:03:02,710 --> 00:03:05,230 And actually, this code looks kind of correct. 49 00:03:05,320 --> 00:03:11,590 And now I want to move our initial URL and results here to the bottom and right console.log. 50 00:03:11,800 --> 00:03:12,970 Result yourself. 51 00:03:13,180 --> 00:03:14,530 And let's check what we have. 52 00:03:14,830 --> 00:03:20,920 AMD allowed in the page and we'll get an exact list less post slash one slash common slash three, which 53 00:03:20,920 --> 00:03:24,760 actually means this logic was reduced, is working correctly so well. 54 00:03:24,760 --> 00:03:26,530 We've been through every single replacement. 55 00:03:26,890 --> 00:03:31,110 Here we updated our euro and here return it and all looks good. 56 00:03:31,120 --> 00:03:33,450 But actually, you have a huge problem. 57 00:03:33,640 --> 00:03:39,190 As you can see, my accumulator variable is not highlighted, which actually means we're not using here 58 00:03:39,190 --> 00:03:42,710 reduced correctly and we're not using accumulator at all. 59 00:03:43,000 --> 00:03:49,570 What we're using, we're using this URL from params and we directly mutate this hotel every single time. 60 00:03:49,780 --> 00:03:51,550 And actually, this is completely wrong. 61 00:03:51,760 --> 00:03:54,460 First of all, because we should not mutate our programs. 62 00:03:54,700 --> 00:04:00,910 And secondly, the most important, but we're using here reduce like a for loop because actually, we 63 00:04:00,910 --> 00:04:06,640 simply mutate our variable from outside in the loop and we're not using our accumulator. 64 00:04:06,940 --> 00:04:13,000 Actually, the correct code here is not here to replace, but simply return accumulator replace. 65 00:04:13,210 --> 00:04:18,700 Because as you can see, we're provided your role here as an initial value and we should not use URL 66 00:04:18,700 --> 00:04:19,570 here inside. 67 00:04:19,780 --> 00:04:21,640 We don't want to change our URL. 68 00:04:21,820 --> 00:04:26,770 We want every single time to update our accumulator and return in your accumulator. 69 00:04:27,010 --> 00:04:31,570 And as you can see, this code is working in exactly the same, but this is completely different. 70 00:04:31,780 --> 00:04:37,090 Previously, if you would write code like this, this is completely wrong on the interview because you 71 00:04:37,090 --> 00:04:39,010 are not using reproduce, like reduce. 72 00:04:39,130 --> 00:04:42,340 But just like for loop, the same goes with map. 73 00:04:42,490 --> 00:04:46,120 If you are using the map just to look through things, you are doing it itron. 74 00:04:46,270 --> 00:04:49,780 With Map, you need to transform your array and return it back.