Answer 1

if you talking about this

function switchType(id) {
var inp = document.getElementById(id);
inp. type =
(inp.type=='password') ? 'text' : 'password';
}

the explanations is as follows:
you have your input tag for the checkbox
<input type="checkbox" name="show" onclick="switchType('pw')">

when clicking it, the function is called and the id of the other input box which contains the password is passed to it

all the JS code does is getting the element reference using the getElementById method and changing its type attribute from password to text and vice versa

Answer 2

click on the checkbox -> the function is called -> the js code changes the input attribute "type" to password (shows *****) or to text according to the current "type"

Answer 3

he could do it without passing the "pw" and just do getElementById("pw")

i guess it makes the function more generic this way

tip:
every one have their own style of coding

don't try to understand WHY someone did something the way he/she did

but rather WHAT he/she did

Answer 4

he could use it for other purposes
jn this case not so much because it still does something quite specific as targeting another input element id and changing it "type" attribute

again
don't focus on WHY
but on WHAT

Answer 5

id is sent as "pw"

it makes it more generic
that's all

Answer 6

master google has allll the answers 😮