1
00:00:00,270 --> 00:00:07,310
Similar to CSX JavaScript functions are most commonly placed in between the open and close had tags.

2
00:00:07,320 --> 00:00:13,320
The reason for this is because the head portion of an HMO page gets loaded before any other part of

3
00:00:13,320 --> 00:00:20,970
the HMO document so if you were to put your javascript code right before the closing body tag any javascript

4
00:00:20,970 --> 00:00:26,790
call is made to functions by your page as it loads will result in an error.

5
00:00:26,820 --> 00:00:33,120
Let's take a look at an example of a javascript function located in our head tag and called upon in

6
00:00:33,120 --> 00:00:34,350
our body.

7
00:00:34,350 --> 00:00:39,830
We won't get too much into the HDMI El here because by now most of this HCM El code should look familiar

8
00:00:41,140 --> 00:00:45,090
but this javascript code will calculate your age in dog years.

9
00:00:45,400 --> 00:00:50,760
A year of a person's life is equivalent to seven years of a dog's life.

10
00:00:50,860 --> 00:00:53,680
Let's preview this file before we take a look at the code

11
00:00:59,190 --> 00:01:03,560
as you can see we input our age in the first input field.

12
00:01:03,690 --> 00:01:11,470
I'll put one just for demonstration once we press calculate the javascript function is called it reads

13
00:01:11,470 --> 00:01:16,120
the value in the first input and multiplies it by 7.

14
00:01:16,120 --> 00:01:18,340
It places the result in the second input

15
00:01:25,590 --> 00:01:33,480
in the code we can see that the script for the javascript function is located in the head tag the function

16
00:01:33,480 --> 00:01:42,790
itself is called C years this function takes the value of the form element my age and multiplies it

17
00:01:42,850 --> 00:01:46,080
by 7.

18
00:01:46,100 --> 00:01:54,160
The result is then displayed in the form element dog age the entire function is activated when the user

19
00:01:54,160 --> 00:01:56,050
clicks the calculate button.

20
00:01:56,980 --> 00:02:03,730
This is when the javascript function is called we can see and on click event attached to the button

21
00:02:04,550 --> 00:02:07,650
we'll explore different events later in this course.