Using $timeout in service: this.func is not a function

Question

I've been trying to use promise to end user session after certain amount of time.

Problem is, whenever a function defined in service is called from the function triggered by $timeout, the function seems to be undefined. I think it's some kind of a scope issue, but I have not managed to fix this on my own.

app.service('sessionService', function($timeout) {
    var closeSession = function() {
        this.resetUserInfo()
        // maybe do other things as well
    }

    this.start = function() {
         console.log("start")
         promise = $timeout(closeSession, sessionLength)
    }

    this.resetUserInfo = function() {
        // reset session
    }
}

Error: this.resetUserInfo is not a function

Things I have tried

different ordering of functions
this.closeSession instead of var
$timeout(function(){closeSession(this.resetUserInfo)}, sessionLength) with proper modifications to closeSession

Possible duplicate of [How does the “this” keyword work?](http://stackoverflow.com/questions/3127429/how-does-the-this-keyword-work) — Grundy, Dec 03 '15 at 11:24
_this_ inside function, depends on how function calling. In your case _this_ not referse to service when function call as callback in $timeout — Grundy, Dec 03 '15 at 11:27

score 3 · Accepted Answer · answered Dec 03 '15 at 11:25

3

Note this assigned to that. So you are using the scope of the service instead of the scope of the method.

 app.service('sessionService', function($timeout) {
    var that = this;
    var closeSession = function() {
        that.resetUserInfo()
        // maybe do other things as well
    }

    this.start = function() {
         console.log("start")
         promise = $timeout(closeSession, sessionLength)
    }

    this.resetUserInfo = function() {
        // reset session
    }
}

answered Dec 03 '15 at 11:25

Simone Zandara

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That worked :) Thanks. This now really seems like a duplicate, but I didn't know to search for right keywords. – Kelo Dec 03 '15 at 11:30
No worries, you can try to read more on how the javascript scope works. – Simone Zandara Dec 03 '15 at 11:32

score 0 · Answer 2 · answered Dec 03 '15 at 11:31

An alternative would be to make resetUserInfo a local function and then attach to it this later on. For example:

app.service('sessionService', function($timeout) {

    //private definition
    var resetUserInfo = function() {

    }

    var closeSession = function() {
        resetUserInfo(); //call the private version
    }

    this.start = function() {
         console.log("start")
         promise = $timeout(closeSession, sessionLength)
    }

    //now expose method as public here
    this.resetUserInfo = resetUserInfo;

}

Using $timeout in service: this.func is not a function

2 Answers2

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