how can I use a function which is located inside a service? - angularjs

Question

What I am trying to do is to use function globally throughout controllers.
The problem is when I want to use the function I defined inside the service in the first function. It shows an error that it cannot find a function. I tried without this keyword but it's not working. I can go to all function when I tried in other controllers, which is a good sign that I can use this service globally.
In short, I want to use all function inside first function.
app.factory("UserService", function() {
var users = ["Peter", "Daniel", "Nina"];
return {
all: function() {
return users;
},
first: function() {
var users = this.all();
return users[0];
}
};
});
The code above was an example that I made and real code appears like this.
controller
angular.module("app").requires.push("app.region");
I put the region to app so I can use the service.
After that I made a controller like this
.controller("regionCreateController", ["$scope", "phoneMaskService", function ($scope, phoneMaskService) {
$scope.createClicked = function (data) {
data = phoneMaskService.putMaskOnRegion(data);
console.log(data);
};
}
When I put phoneMaskService which is the service I made in the app.js and it fails.
This is the error I am getting
angular.js:14110 ReferenceError: removeAllLetters is not defined
This is the actual code making errors.
.factory("phoneMaskService", [function () {
var returnMethod = {
removeAllLetters: removeAllLetters,
putMaskOn: putMaskOn,
putMaskOnRegion: putMaskOnRegion
};
return returnMethod;
function removeAllLetters(value) {
var val = value.replace(/\D+/g, '').replace('\-', '');
return val;
}
function putMaskOn(value) {
console.log(value);
value = this.removeAllLetters(value);
console.log(value);
var isMobile = parseInt(value.charAt(1)) == 2;
if (isMobile) {
var x = value.replace(/\D/g, '').substring(0, 14).match(/(\d{3})(\d{3})(\d{3,})/);
x = ' ( ' + x[1] + ' ) ' + x[2] + ' - ' + x[3];
return x;
} else {
var x = value.replace(/\D/g, '').substring(0, 14).match(/(\d{2})(\d{3})(\d{3,})/);
x = ' ( ' + x[1] + ' ) ' + x[2] + ' - ' + x[3];
return x;
}
}
function putMaskOnRegion(object) {
angular.forEach(object, function (value, key) {
if (key == "contactNumberPhone") {
var testvalue = this.removeAllLetters(value);
console.log(this);
console.log("test value" + testvalue);
object[key] = this.removeAllLetters(value);
}
});
return object;
}
}])
The error happens the line here and says removeallletters are undefined
var testvalue = this.removeAllLetters(value);

Answer 1

One approach to avoid binding problems is to declare the functions inside the factory:
app.factory("UserService", function() {
var users = ["Peter", "Daniel", "Nina"];
return { all: all, first: first };
function all() {
return users;
}
function first() {
var users = all();
return users[0];
}
});

Answer 2

I use the follwoing when declaring factories, which
creates an object within the factory declaration, binds methods to it and returns is as the the factory object.This might work in your case.
app.factory("UserService", function() {
var services = {};
services.users = ["Peter", "Daniel", "Nina"];
services.all = function() {
return services.users;
}
services.first = function() {
return services.all()[0];
}
return services;
});