What is the official correct way to declare jQuery variables?

Question

I am trying to learn jQuery. I keep seeing people using different methods of declaring variables.

I have seen var variable; , var $variable; , and $variable; . Which one (if any of these) is the official correct way to declare jQuery variables.

Answer 1

You should always declare a variable with var (whatever the scope, unless creating it on an object), implied globals are bad, don't do it.

As for variable vs. $variable , there is no official stance, just have a convention that you and your team stick to.

As a general rule some follow, (I don't follow this, some do), use variable for variables that aren't jQuery objects and $variable for variables that are, those who use this typically find that seeing $something and knowing immediately it's a jQuery object to be handy.

Answer 2

Use var to define variables to ensure that they are scoped properly, usually locally within a function. My convention is to use $variable when the variable holds a jQuery object (result of a selector) and variable for everything else.

BTW -- they aren't jquery variables, but rather javascript variables. JQuery is just another (albeit the most popular at present) javascript framework, not a language in and of itself.

Answer 3

There is no official correct way to declare variables for jQuery..

They are all javascript variables, and these are the rules for javascript variables

Using the $ at the beginning is a convention that the variable is holding a jQuery object ( since the jquery uses the $ sign for the function wrapper )

The diffeernce of using var or not, is in the scope of the variable. Using var declares it local, not using var adds it to the global scope.

Answer 4

Nick already explained why you should use var .

The reason behind variable and $variable is that $ is associated with jQuery and should imply that this variable holds a jQuery object. To avoid unnecessary function calls to jQuery like $(variable) where variable actually already holds a jQuery object.

Answer 5

There is no such thing as a "jQuery variable", they are Javascript variables. When learning jQuery you have to learn some Javascript, as jQuery is just a library for Javascript.

You declare a variable using the var keyword. You can also use a variable without declaring it, and it will implicitly be declared as a global variable, but that is not recommended. You should declare variables in the scope where they are used.

Sometimes putting a $ sign as the first character of a variable name is used to indicate that it's intended for containing a reference to a jQuery object, however there is no official recommendation, and the language itself doesn't care what you name your variables.

Answer 6

The ones with var are local variables, the one without it is global. So it's not just a matter of style. Apart from that use anything you like, personally I haven't seen "$" prefixed variables, but maybe they are useful if you mix a lot of jQuery and standard JavaScript code.