2

http://jsfiddle.net/hRksW/

function test() {
    this.alerting = function () {
        alert("test");
    };
    this.something = function () {
        setInterval(function () {
            this.alerting();
        }, 1000);
    };

}

var a = new test();
a.something();

Calling the function something() should call the function alerting() every second. This should alert 'test' every second. Why doesn't that happen and how can I make it happen? Note that I want to keep this design of calling a method in a method, if possible.

George Irimiciuc
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    Relevant: [JavaScript “this” keyword](http://stackoverflow.com/q/3127429/251311) – zerkms Jul 14 '14 at 10:04
  • It does not happen because `this` is not a variable. It's a keyword that refers to the owner of current context. Inside an anonymous function it will be the global `window` (or `undefined` if in strict mode). – freakish Jul 14 '14 at 10:24
  • @zerkms that link was really helpful – George Irimiciuc Jul 14 '14 at 13:41

6 Answers6

2

http://jsfiddle.net/N6hPB/

function test() {
    this.alerting = function () {
        alert("test");
    };
    this.something = function () {
        setInterval(this.alerting, 1000);
    };    
}

var a = new test();
a.something();
zavg
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2

Store a reference of this in a variable and use it for method that run outside of the current context (like the setInterval does)

function test() {
    var that = this;

    this.alerting = function () {
        alert("test");
    };
    this.something = function () {
        setInterval(function () {
            that.alerting();
        }, 1000);
    };

}

var a = new test();
a.something();
Gabriele Petrioli
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  • This seems to work, but why do I have to store 'this' in a variable and why isn't my code working? – George Irimiciuc Jul 14 '14 at 10:26
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    @GeorgeIrimiciuc, `this` inside setInterval's function parameter belongs to inner function context, not outer context, `this` always refers to current context – Yuliam Chandra Jul 14 '14 at 10:29
  • @GeorgeIrimiciuc, what Yuliam said. `this` is a special keyword and its content is specified by the context the function is running. The `setTimeout` context is the `window` so `this` inside methods triggered by `setTimout` point to the `window`. – Gabriele Petrioli Jul 14 '14 at 11:00
0

Hope this helps! Here the timer is in ms.

function something(){
   window.setInterval(alerting, 1000); 
}

function alerting() { 
  alert('test'); 
}
Aravind
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0

Another way to do it is returning an object instead.

function test() {
    var self = {
        alerting : function () {
            console.log("test");
        },
        something : function () {
            setInterval(function () {
                self.alerting();
            }, 1000);
        }
    };
    return self;
}

var a = new test();
a.something();
Yuliam Chandra
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0

You can do it making an object with functions, and then call them without instantiating it. 

var testCaller = {
    alerting: function() {
       alert("test")
    },
    something: function() {
       // Store current scope
       var self = this;
       setInterval(function() {
           self.alerting();
       }, 1000);
    }
}

testCaller.something();
wIRELESS
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0

You can try this code. I have tested it, and it works. In your code, "this" pointer points to somewhere else.

function test() {

    test.prototype.alerting = function() {
        alert("alert test");
    };

    test.prototype.something = function () {
        setInterval(this.alerting, 1000);
    };
}

var a = new test();
a.something();
Mahdi Saber
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