I see sometimes js snippets that are using the $ in front of the argument ($argName).

function someName(arg) {
  // some code
  // using arg
}

function someName($arg) {
  // some code
  // using $arg
}

In this js example it works either way with or without the $ in front of the arguments. Can anyone explaine if it has any use?

I see sometimes js snippets that are using the $ in front of the argument ($argName).

function someName(arg) {
  // some code
  // using arg
}

function someName($arg) {
  // some code
  // using $arg
}

In this js example it works either way with or without the $ in front of the arguments. Can anyone explaine if it has any use?

• javascript

• 1 The "$" character is just a character that can be used in an identifier - there's nothing special about it. – Pointy Commented Mar 19, 2015 at 14:14
• 3 some people use it as a convention to name a jQuery element or an angular builtin service. – Daniel A. White Commented Mar 19, 2015 at 14:15
• Hungarian notation why people only use it for jQuery object drives me mad. – epascarello Commented Mar 19, 2015 at 14:25
• @epascarello I find it useful as it reminds colleagues that they needn't rewrap the parameter in another $() call. It's a long way from full MS-style Hungarian notation IMHO, and more useful given that JS isn't a strongly typed language. – Alnitak Commented Mar 19, 2015 at 14:49
• @Alnitak JSDoc or any other code documentation seems to fix that problem without making a special case exception for one variable type. – epascarello Commented Mar 19, 2015 at 15:30

2 Answers 2

The $ character is legal in JS identifiers, and is often used simply as a code convention to indicate that the passed parameter is already a jQuery object (as opposed to a native DOM element).

This serves as a reminder that it's not necessary to re-invoke the jQuery $(param) wrapper function on that parameter.

It's also used quite a lot in Angular JS code.

It's sometimes used to reference an object from another library , like JQuery or AngularJS , what you're talking about here looks like AngularJs's dependency injection to me

UPDATE

See this answer it might be useful