I'm doing a redux tutorial, and I saw a call like this:
this._render();and it's defined elsewhere as:
_render() { ....
} What is the underscore "_"? Why is it used?
13 Answers
This is convention of private methods and variables. In JavaScript there is no real privacy of classes.
It means that you should not use these method (starting with "_") out of your object. Of course technically you can, but "_" means that you should not.
Underscore (_) is just a plain valid character for variable/function name, it does not bring any additional feature.
However, it is a good convention to use underscore to mark variable/function as private. You can check Underscore prefix for property and method names in JavaScript for some previous discussion.
The underscore is simply a valid character in an identifier, so the method's name is _render.
It's a common pattern in languages without access modifiers to use underscores to denote private methods. In a language such as C#, which does have access modifiers, I could define a method as:
private void Foo() {}The method Foo can then only be called from within the class which defined it.
In JavaScript you can't do this, so it's a typical design pattern to prefix the method with _ to show that it should be treated as private.
this._foo();You can still call this method, it's just not considered good practice to do it outside of the class definition.
