What's the difference between following types of var declaration in JavaScript?
$x
var x
var $x
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4 Answers
$x and x are simply two different variable names. Like var x and var y. Simply using $x is an implied declaration, except that if $x exists in a higher scope, you'll use it. declaring var $x sets up a new $x in the current scope which avoids conflicts with any other $x at a higher scope.
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No difference except for scope. $x is just a variable name like x. var creates variables in a local scope, otherwise they are global.
This has nothing to do with jQuery, really.
1 Comment
Zhihao
This answer may seem confusing given the current content of the question since there is no longer any tag or mention of jQuery. To elaborate,
$x and x variable names are no more different than xy and x. However, $ is sometimes used at the beginning of variable names by convention to indicate that the variable stores a reference to a jQuery object.If you use $x without declaring it, you are implicitly creating a global variable called $x. var x and var $x each create a variable in whatever function (or global scope) you're in, called x and $x, respectively. Neither has anything to do with jQuery.
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Nothing. I find it good practice, however, to precede variable names with a $ if it returns a jQuery object and without if it returns a DOM object or other type (string, etc.)
The term 'var' is useful for determining scope. Always use 'var' on first declaration, or on anytime you need a variable to be local in scope.
