WEBVTT 00:00.840 --> 00:06.960 It's time to talk about the next important concept in JavaScript, which is called operators, so what 00:06.960 --> 00:07.920 is an operator? 00:08.400 --> 00:13.050 Operators of special functions that take two parameters and return results. 00:13.680 --> 00:17.190 You may already know some of them, especially from your math class. 00:17.610 --> 00:18.080 What do we see? 00:18.090 --> 00:20.130 For example, five plus five. 00:21.250 --> 00:27.520 We all know that we have to add those numbers because plus generally means additions and therefore the 00:27.520 --> 00:28.510 result is 10. 00:29.700 --> 00:33.000 Now, let's see what happens in JavaScript creates variable A. 00:34.420 --> 00:36.430 And assigned to it five plus five. 00:39.250 --> 00:40.720 And then run it in Castle. 00:43.100 --> 00:43.970 You see, we have. 00:45.410 --> 00:49.280 So how does JavaScript and you know that it has to add these numbers? 00:49.880 --> 00:55.700 The reason is that it's already built there the right function, which is automatically called one JavaScript 00:55.700 --> 01:00.200 engine system, plus as the numbers and gives us the results. 01:01.400 --> 01:03.680 In the same way, works subtraction. 01:05.930 --> 01:06.860 Multiplication. 01:08.780 --> 01:10.050 And division. 01:12.140 --> 01:21.470 All right, sometimes we are using multiple operations in one statement, like five plus five and multiplied 01:21.470 --> 01:21.990 to five. 01:22.790 --> 01:28.560 So what do you expect to get here because of that JavaScript and generates the code from left to right? 01:29.090 --> 01:35.030 You may think that first it would add five to five and then multiply it to another five, which then 01:35.030 --> 01:36.370 will output 50. 01:37.610 --> 01:38.660 Let's see what happens. 01:39.710 --> 01:44.840 You said that we got 30 because it follows the exact same rules. 01:44.840 --> 01:50.900 As we know from math at first, JavaScript engine multiplies and then performs additions. 01:51.870 --> 01:58.620 In JavaScript, it's called Operator Precedent's, you can look into the table where Operator Precedent's 01:58.620 --> 01:59.520 is represented. 02:00.180 --> 02:03.180 Let's search it in Google, right. 02:03.180 --> 02:05.250 Operator Precedent's table. 02:08.340 --> 02:15.210 You can visit this website developer, Dot Mozilla dot org, which actually is very useful guide for 02:15.210 --> 02:19.890 JavaScript, and you can find almost everything regarding JavaScript on that site. 02:20.580 --> 02:21.060 All right. 02:21.540 --> 02:23.580 So here we have operator precedence. 02:23.580 --> 02:30.060 Table first column represents precedence number, which defines the sequence of the operations. 02:30.690 --> 02:36.360 As you remember from the previous example, JavaScript engine has performed at first multiplication 02:36.360 --> 02:37.400 and then addition. 02:38.040 --> 02:44.850 And if you look at the table, you will see that multiplication has precedence of 14, which is higher 02:44.850 --> 02:47.410 than the precedence of addition, which is 13. 02:48.120 --> 02:52.080 You also see that addition and subtraction have the same number of precedence. 02:52.590 --> 02:59.640 It means that JavaScript engine will perform operation from left to right, and it's called associativity. 03:00.540 --> 03:06.640 Some of the operators have associativity from left to right and some of them have right to left. 03:07.230 --> 03:09.600 It also depends on type of operator. 03:10.980 --> 03:15.350 The highest number of precedence has grouping operator, which is parentheses. 03:16.290 --> 03:23.400 So if we pass the addition with embraces, the result will be different and will get 50. 03:24.560 --> 03:31.160 All right, operator Preston's table is a very useful source, you can find their operator we are interested 03:31.160 --> 03:31.420 in. 03:31.820 --> 03:37.250 I recommend to review this table and introduce to other operators and figure out how they work. 03:38.340 --> 03:45.300 All right, so we have talked about arithmetical operators and also discussed what operator precedence 03:45.300 --> 03:46.880 and Associativity are. 03:47.400 --> 03:48.720 See you in the next lecture.