What value does the dollar symbol ($
) in JavaScript? What is he answering and where is it appropriate to use?
Answer 1, Authority 100%
It can be used as a short and non-trivial name for a variable. This is done in many JavaScript frameworks. For example jQuery and Prototype.
Answer 2, Authority 127%
Nothing special, just this symbol can be used in identifiers, unlike many other languages. That is, ABC $ def
– the legitimate name of the variable or function, for example.
You did not confuse JavaScript with the jQuery library? In it, $
is used under the global variable. Again, no magic, just the name of the variable.
Answer 3, Authority 55%
In JavaScript A $ sign is used to interpolation of expressions:
let data = [11, 22, 33];
Const str = `Number $ {Data [0]} from Data`;
Console.log (STR); // Number 11 FROM DATA
(only replace ‘on`)
Answer 4, Authority 45%
is a regular symbol.
var one $ two = true;
alert (one $ two);
Also also a dollar sign is used to access the main object JQuery
if this library is connected.
or $ (id)
in prototype
means
document.getelementbyid (id)
Answer 5
& lt; form & gt;
User: & lt; input name = "username" type = "text" & gt; & lt; br & gt;
Email: & lt; Input name = "Email" Type = "Text" & gt;
& lt; / form & gt;
& lt; script & gt;
$ ('[Name = "UserName"] "). Val (app.user.username);
$ ('[Name = "Email"]'). Val (app.user.email);
& lt; / script & gt;
There is a joke in that it is not necessary to use
document.getelementsbyname ('username')
Document.getelementsByname ('Email')
And you can simply specify $ to access the JQuery main object (as mentioned above)
Answer 6
& lt; form & gt;
User: & lt; input name = "username" type = "text" & gt; & lt; br & gt;
Email: & lt; Input name = "Email" Type = "Text" & gt;
& lt; / form & gt;
& lt; script & gt;
$ ('[Name = "UserName"] "). Val (app.user.username);
$ ('[Name = "Email"]'). Val (app.user.email);
& lt; / script & gt;
Here you have a good example of using $!
I think everything became clear …