The problem with the function scope object

JavaScript provides you with standard means to ensure the desired context:

• You can pass parameter for the function in

  setTimeout(function(_, otherParms,...){
  _.memberOfContextObject;
  _.memberOfContextObject();
  }, timeoutTimeInMS, contextObject, otherParms,...);
  

• Alternative is to bind the function and then pass to `

  setTimeout(function(otherParms,...){
  this.memberOfContextObject;
  this.memberOfContextObject();
  }.bind(contextObject), timeoutTimeInMS, otherParms,...);
  

• This works too, but is not as flexible as above options:

  function anyFunctionOfThis() {
  var _this = this; // create non-this reference of this
  setTimeout(function(otherParms,...){
    _this.memberOfContextObject;
    _this.memberOfContextObject();
  }, timeoutTimeInMS, otherParms,...);
  

As you know, you can defined the function as a named function outside of setTimeout(... or setInterval(... or ..., functionAsCallbackParm,...either as function or 'method of an object' (see object-oriented programming with JS). I use this when I have to provide them as callbacks in multiple places:

var fun      = function(otherParms,...) { ... };
var funBound = fun.bind(contextObject);

setTimeout(funBound, timoutTimeInMS, otherParms,...

There are many options and combinations there of you can chose from for the optimal use in your situation.

For the alternative 'this', I use the _this or short form of it _ to indicate that it is about the this / context object. I've also seen that to be used. But I prefer a more eye catching - and short - form, therefore: _ is my choice.