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JavaScript

Posted by Byron Farrell
Byron Farrell
5,700 Points

What is the purpose of the dollar sign before the variable scope i.e. $scope?

What does the $ sign as the first character of a variable mean?

Dave StSomeWhere
Dave StSomeWhere
19,870 Points

In what context?

Some people use it to convey a meaning but as far as JavaScript is concerned it is just another valid identifier.

From MDN Identifier

In JavaScript, identifiers can contain only alphanumeric characters (or "$" or "_"), and may not start with a digit. An identifier differs from a string in that a string is data, while an identifier is part of the code. In JavaScript, there is no way to convert identifiers to strings, but sometimes it is possible to parse strings into identifiers.

Byron Farrell
Byron Farrell
5,700 Points

Hey Dave,

I only asked because I am doing the angular tutorial and a parameter was named $scope and I just thought it was a special icon for a special type of variable. Thanks for replying :)

Dave StSomeWhere
Dave StSomeWhere
19,870 Points

Aha, that's why I asked about context.

Looks like the angular peeps use do use it - some searching should help you see what and why they use it - I'm not up on angular so will stop babbling now :tropical_drink: :palm_tree:

1 Answer

Sean T. Unwin
Sean T. Unwin
28,690 Points

Words prefaced with a dollar sign ($) in Angular are custom objects within the Angular engine ,similarly to jQuery where $() is reference to a jQuery Object, which in turn typically references a DOM element.

Info on Scopes in Angular: Angular: What are $scope's